Crown Cementation: Clinical Guidelines, Tips, and Best Practices for Success

Understanding Crown Cementation

Crown Cementation is a crucial step in clinical dentistry, as this process directly affects the dental crown’s durability, aesthetics, and functionality. It requires careful and precise consideration to ensure long-term success and optimal outcomes. Using inappropriate materials or techniques can lead to premature crown failure, resulting in additional costs for both the dentist and the patient. Therefore, a thorough understanding of the properties and functions of different types of dental cements, as well as the crown cementation procedure, enables dentists to select the most suitable cement for the patient’s specific condition and achieve the best possible clinical results.

Commonly Used Types Of Cement

Based on the type of crown material, aesthetic requirements, longevity needs, and the dentist’s preference, an appropriate cement with suitable characteristics and functions will be selected. Dental cements can be categorized into two main types: soft cements and hard cements.

Soft cements are primarily used for the temporary cementation of permanent crowns during the evaluation and trial period (such as when occlusion or aesthetics undergo significant changes). In contrast, hard cements are used for permanent cementation.

In this article, we will explore different types of hard cements, including Resin Cements, Glass Ionomer Cements (GIC), Zinc Phosphate Cements, Resin-Modified Glass Ionomer Cements (RMGIC), and Self-Adhesive Resin Cements. Each type of cement has its advantages and limitations, and the selection should be based on a deep understanding of the specific clinical situation that will help achieve the best results in the crown cementation process.

Resin cements

Due to their excellent aesthetics, high bond strength, and versatility, resin cements are among the most commonly used cements in the crown cementation process. They provide strong adhesion, high bond durability, good mechanical resistance, and low solubility in the oral environment.

Additionally, resin cements exhibit good translucency and color stability, making them an ideal choice for crown materials such as ceramics and composites, particularly in anterior restorations where aesthetics are crucial. With various curing mechanisms, including light-cure, self-cure, and dual-cure, resin cements can easily adapt to different clinical situations, offering greater flexibility in dental restorations.

Resin cements

Self-Adhesive Resin Cements

Self-adhesive resin cements are a relatively new type of resin cement that offers ease of use and simplifies the crown cementation process by eliminating the need for separate etching and bonding steps. They combine the advantages of traditional resin cements and ionomer-based cements, providing both convenience and high durability in fixed prosthodontics.

Thanks to their self-etching or self-priming properties, they can bond effectively to both tooth structure and crown materials. This makes them a suitable choice for a wide range of materials, from PFM and cast metal restorations to zirconia and alumina core ceramics.

Self-Adhesive Resin Cements

Glass Ionomer Cements (GIC)

Glass Ionomer Cements (GIC) have a unique characteristic of releasing fluoride ions, which helps prevent secondary caries. Their ionic bond between the ionomer glass and the calcium and phosphate ions in enamel and dentin provides good adhesion to dentin.

Although GICs have lower bond strength compared to resin cements, they offer certain advantages, such as biocompatibility and fluoride release. They are particularly suitable for use with PFM or all-metal restorations on teeth and metal implants, cast-metal posts and cores, and prefabricated metal posts.

Glass Ionomer Cements (GIC)

Zinc Phosphate Cements

As one of the oldest dental cements, Zinc Phosphate Cements have been widely used for many years in crown cementation. Despite advancements in digital technology leading to the development of various other cements, Zinc Phosphate Cements remain a reliable choice in many clinical situations due to their high durability, strong mechanical resistance, and insulating properties.

However, their aesthetic limitations and potential for pulp irritation make them primarily used for cementing metal crowns and bridges, particularly in posterior regions where aesthetics are less of a concern.

Zinc Phosphate Cements

Resin-Modified Glass Ionomer Cements (RMGIC)

Resin-Modified Glass Ionomer Cement (RMGIC) is currently one of the most widely used dental cements, accounting for approximately 52% of usage (according to research from the National Dental Practice-Based Research Network).

RMGIC combines the benefits of both resin cements and glass ionomer cements, offering improved aesthetics, higher bond strength, and mechanical properties similar to resin cements while retaining key characteristics of GIC, such as fluoride release and chemical bonding to tooth structure. It is an ideal choice for cementing crowns, bridges, orthodontic appliances, and as a base or liner in restorations.

Resin-Modified Glass Ionomer Cements (RMGIC)

Steps For Crown Cementation

For each different crown material, the crown cementation process will include specific steps. However, the general procedure consists of the following steps:

Restoration Preparation

Most crowns require preparation before cementation by etching or decontaminating the internal surface. This step helps remove stains or any contaminants that may have adhered to the restoration during the trial phase, such as saliva, astringents, desensitizers, disinfectants, and temporary cement. Additionally, it enhances bond strength and reduces microleakage. There are several methods for decontamination, including sandblasting, airborne particle abrasion, zirconia cleaning solutions, or hydrofluoric acid treatment.

Cement Application

Dispense a small amount of cement onto the mixing pad, then mix thoroughly according to the manufacturer’s instructions and apply it in a controlled manner. Next, inject the cement directly into the crown and firmly press it onto the prepared tooth using finger pressure for the recommended setting time, ensuring that all contact areas with the tooth are fully covered until the crown is securely seated. Finally, carefully remove any excess cement to prevent cement-induced gingival inflammation and other complications.

Excess Cement Removal

The final step is to carefully remove any excess cement to prevent potential gingival inflammation and other complications. Specifically, for resin cements, perform an initial light cure (1–2 seconds), then remove excess cement using a scaler or dental floss. For RMGIC, wait until the cement reaches the gel phase, then clean the crown margins to ensure proper finishing.

Cure

Light cure the cement per the manufacturer’s instructions. Be sure to pay attention to the details regarding surfaces and distances involved with the curing light position. Once the cement has achieved the timing and curing required, finish and polish the restoration as desired.

Key Considerations for Crown Cementation

• Removal of excess cement at the time of crown cementation is essential to preserve periodontal health. Failure to thoroughly remove excess cement during clean-up results in it acting as a gingival irritant. Excess cement has a rough surface that encourages bacterial colonization and biofilm accumulation, which leads to gingival inflammation with local swelling and bleeding
• Carefully read all cement instructions and store them properly to ensure they perform at their best. If the cement requires refrigeration, make sure to take it out at least one hour before use, allowing it to gradually reach room temperature.
• Carefully control the cement thickness for each specific type to achieve maximum bond strength, as it determines 70% of the success of the crown cementation process. A cement layer that is too thin may have higher stress concentrations compared to a slightly thicker layer. However, an excessively thick cement layer is also undesirable, as it becomes more prone to fracture.
• Control the applied force to ensure the crown is seated completely. If the force is too strong and applied suddenly, it may cause the tooth to rebound elastically, leading to partial crown dislodgement. Conversely, if the force is too weak, the bond may lack sufficient strength.
• The crown margin, where it meets the tooth structure, must fit tightly to prevent bacterial infiltration beneath the crown. Gaps or irregularities along the margin can increase the risk of bacteria and food debris accumulation, leading to potential secondary caries.

Summary

Crown cementation is a crucial step in restorative dentistry that requires meticulous attention to detail. From pre-cementation preparation to selecting the appropriate cement, applying proper cementation techniques, and ensuring post-cementation care, each stage significantly impacts the long-term success of the crown restoration.

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