What are Dental Cements?

Dental cements are essential for securing dental restorations like inlays, crowns, and bridges in place, similar to everyday adhesives. They serve various purposes in dentistry based on the specific material and procedure. Dental cement is a material formed by mixing components like powder and liquid. It is used to secure dental restorations, prevent microleakage, and maintain restoration stability over time. The key principle is ensuring friction between the tooth and the restoration. This process involves three surfaces: the tooth, cement, and prosthesis. Cements can be categorized into two main groups: conventional/non-adhesive and adhesive. Adhesive cements adhere better to tooth surfaces, providing improved retention and marginal sealing, while conventional cements rely on mechanical retention and do not interact as intimately with dental abutments.

Types of dental cements:

Dental cements can be classified according to their chemical composition and clinical application:

Classification based on the Chemical Composition
Material	Type Of Reaction	Formulation/ Components
Resin- reinforced glass ionomer cement	Acid- base& Chemical	Powder: aluminium oxide (Al2O3) Liquid: polyacrylic acid (C3H4O2) Hydroxyl methyl acrylate HEMA Group
Resin Cement	Chemical Based Reaction	Hydroxyl methyl acrylate HEMA Group Carboxylic Acid CO2H Barium silicate glass
Zinc Phosphate Cement	Acid-Base	Powder: Zinc Oxide (Zno) Liquid: orthophosphoric acid (H3PO4)
Cement- Polycarboxylate		Powder: Zinc Oxide (Zno) Liquid: Polyacrylic acid (C3H4O2)
Conventional Glass ionomer Cement		Powder: Aluminium oxide (Al2O3) Liquid: polyacrylic acid (C3H4O2)

Classification based on their Clinical Use
Speciality	Uses
Conservative Dentistry	Temporary Filling
Endodontics	Root Canal Sealing
Orthodontics	Orthodontic Cementing
Surgery	Temporary dressing to heal wounds
Oral Rehabilitation	Cemented joint prosthesis
Preventive Dentistry	Fissure Sealants

Zinc Phosphate Cement:

• Application: This type of cement is frequently used for permanent crown and bridge cementation.
• Features: It is known for its strength and durability, it provides a strong, long-lasting bond between the restoration and the tooth structure.

Polycarboxylate Cement:

• Application: Polycarboxylate cement can serve as a final or intermediate cement. It has also been used for orthodontic purposes and insulating bases.
• Features: This cement is known for its good biocompatibility and ability to release fluoride. It offers a moderate bond strength to tooth structure and is often used when a permanent bond is not needed. It can also be used for patients with sensitivity to other types of cement.

Glass Ionomer Cement:

• Application: This type is used for various applications, including permanent cementation, filling materials, and as a liner or base under restorations.
• Features: Glass ionomer cement can chemically bond to both enamel and dentin, making it versatile. It releases fluoride ions, aiding in the prevention of tooth decay.

Resin-Based Cements:

• Applications: This category includes various resin-based cements like resin-modified glass ionomer cement and self-adhesive cements. They are often used for cementing tooth-coloured restorations, such as composite fillings or ceramic crowns.
• Features: Resin-based cements can provide strong and aesthetic bonds to tooth structure. Resin-modified glass ionomer combines the benefits of glass ionomer and resin cements. Self-adhesive cements simplify the cementation process as they eliminate the need for separate adhesive steps.

Oil-based dental cements:  They have been replaced by water-based cements due to advancements in dental materials. However, there are historical oil-based cements that were once utilized for various dental applications. Here's an elaboration of these types with their features:

Zinc Oxide-Eugenol Cement (Oil-Based):

• Application: Formerly used for temporary cementation, thermal insulation, and as a sedative filling material.
• Features: Zinc oxide-eugenol cement has a soothing effect on dental pulp and is often used for temporary restorations. It has a slow-setting time, making it suitable for procedures where extended working time is needed. However, it has a weak mechanical strength and is not appropriate for long-term use.

Intermediate Restorative Material (IRM) (Oil-Based):

• Application: IRM is a type of zinc oxide-eugenol cement used for intermediate or temporary restorations.
• Features: IRM shares many characteristics with zinc oxide-eugenol cement. It is primarily used for short-term applications, such as temporary fillings. Its oil-based formulation allows for easy mixing and placement. It has sedative properties and can provide relief from tooth sensitivity.

Oil free dental cements: These cements offer improved bond strength and reduced potential for interference with adhesion. The types of oil-free dental cement types with their features are as follows:

Glass Ionomer Cement (Oil-Free):

Application: Glass ionomer cements are versatile and used for various purposes, including restorations, luting (cementing crowns and bridges), liners, and as a base beneath other restorative materials.

Features: Glass ionomer cements have the advantage of chemically bonding to tooth structure (enamel and dentin). They release fluoride ions, which help prevent further decay around the restoration. These cements can be used in both anterior and posterior teeth. They come in various formulations, such as conventional glass ionomers, resin-modified glass ionomers, and high-strength glass ionomers.

Resin-Modified Glass Ionomer (Oil-Free):

Application: Resin-modified glass ionomer cements combine the benefits of glass ionomers with the additional strength and aesthetics of resin-based materials. They are commonly used for luting, restorations, and bonding orthodontic brackets.

Features: These cements have a dual-setting mechanism, combining chemical adhesion (like glass ionomers) with light curing (like resin-based materials). They offer a strong bond to tooth structure and restorative materials. Resin-modified glass ionomers are preferred for aesthetic restorations and can release fluoride.

Composite Resin Cement (Oil-Free):

• Application: Composite resin cements are used for bonding indirect restorations, such as ceramic crowns and veneers, and orthodontic brackets.
• Features: These cements provide excellent aesthetics and bond strength. They can be colour-matched to the tooth, making them ideal for anterior restorations. Composite resin cements are versatile and are used in both anterior and posterior teeth. They are cured with a light source, allowing for precise control over the setting process.

Adhesive Resin Cement (Oil-Free):

• Application: Adhesive resin cements are designed for bonding all-ceramic and zirconia restorations, as well as metal and PFM (porcelain-fused-to-metal) crowns and bridges.
• Features: These cements offer high bond strength and aesthetics. They rely on adhesive systems for bonding, which can be dual-cured or light-cured. Adhesive resin cements are suitable for a wide range of restorative materials and provide reliable and long-lasting adhesion.

Why are Dental Cements used in Dentistry?

Dental cement comes in various types suited for different dental procedures. Dentists use dental cement for various purposes, considering factors like the patient's oral and general health to select the most suitable type of cement for each situation here’s an overview of the different types:

Luting Agent: Dental cements, often referred to as luting agents, are essential for securing dental restorations and appliances. They retain these structures through mechanical means, and precise fit is critical to minimize cement exposure. Their rapid setting, biocompatibility, and resistance to oral fluids are essential characteristics.

Pulp Protection: Dental cements have applications as intermediate bases or liners, particularly when dentin thickness is insufficient, generally under 2 mm. These materials are used between the pulp and the restorative substance.

Cementing Crowns and Bridges: Dental cements are used to bond crowns and bridges in place, ensuring they remain secure and functional within the patient's mouth. These cements provide both micromechanical and micromechanical retention, playing a critical role in luting restorations effectively.

Sealing and Liners: Dental cements serve as effective sealing agents and liners, protecting the tooth's pulp and dentin while sealing potential gaps, minimizing the risk of recurrent decay in dental restorations.

Core Buildups: Dental cements are used for core buildups, providing structural support and anchoring restorations to extensively damaged teeth, helping to restore their strength and function.

Cementing Veneers: Dental cements are used for cementing veneers, providing a secure and aesthetically pleasing bond between the thin veneer and the tooth's surface, enhancing appearance and function.

Temporary Restoration: Dental cements are used for temporary restorations, holding crowns or bridges in place until permanent ones can be fitted, ensuring patient comfort and protection.