If a crown fails, it is always the crown that takes the fall, even when it is actually the cement that caused the failure. Dental cement is the unsung hero of restorative dentistry. In some cases, choosing the right type of luting agent makes the difference between having a crown for ten years and losing one within half a year.
As a dentist seeking knowledge about the cementation techniques for your next crown or as a patient wondering what is involved in the process, this guide provides information on dental cements for crowns, including glass ionomer cement, resin-modified glass ionomer, self-adhesive resin cement and temporary luting agents.
What Is Dental Cement?
Dental cement, which may also be referred to as a luting agent or luting cement, is an adhesive medium employed in the stabilization of dental restorations on a tooth surface or abutment.
Functions of dental cement include the following:
Retention: Ensuring retention of the restoration, through mechanical locking or chemically.
Seal: Achieving a marginal seal in order to prevent microleakage at the tooth-restoration interface, thus preventing secondary decay.
Bio-compatibility: Ensuring that there is no pulpal irritation after placement.
Fluorescence: Release of fluoride ions in certain types of cements (GIC and RMGI) acts as a protective mechanism for the surrounding dentition.
Dental cements can be permanent or temporary, adhesive or non-adhesive based on their chemical composition.
Types of Dental Cement: A Clinical Overview
The following are the five categories of dental cements employed for placing crowns:
1. Glass Ionomer Cement (GIC)
A water-based cement, glass ionomer cement can be described as one of the most versatile cements. Key advantages include:
Chemical bonding with the tooth structure without the need for an additional bonding agent
Ability to release fluoride ions that contribute to the well-being of the enamel
Biocompatibility and reduction in post-operative sensitivity
Simplified handling and forgiving moisture tolerance
Glass ionomer cement is particularly well-suited for PFM crowns, metal restorations and cases where fluoride protection is a priority. For a premium GIC product, the VinciSmile Filling-I Glass Ionomer Cement (GIC) — available at Dentistry99 — is a highly regarded option offering consistent set, reliable adhesion and excellent fluoride delivery.
2. Resin-Modified Glass Ionomer (RMGI)
Resin-Modified Glass Ionomer Cements are an intermediate cement between the glass ionomers and the resin cements. RMGI combines glass ionomer with resin (usually HEMA), resulting in:
Early high strength and decreased early sensitivity to moisture compared to GICs
Fluoride release and improved control of film thickness
Suitable bond strength for most crowns
More tolerance than an adhesive resin cement in the presence of poor isolation
RMGI cement is often used for zirconia crowns with good retention. It is commonly used for PFM and metal crowns on a day-to-day basis. It is regarded as the best all-around crown cement by many clinicians.
3. Resin Cement (Adhesive & Self-Adhesive)
Resin-based cements deliver the highest bond strengths available and are the material of choice for all-ceramic restorations, veneers and minimal-retention preparations. They fall into two sub-categories:
Conventional adhesive resin cement: Requires separate etching, priming and a bonding agent prior to cementation. Offers maximum bond strength but demands excellent isolation and greater technique sensitivity.
Self-adhesive resin cement: Combines the primer, adhesive and cement into a single formulation. Significantly reduces chairtime and technique sensitivity while still delivering high bond strength.
Light-cure or dual-cure systems are commonly used for polymerization.
Clinical Note: For all-ceramic and thin translucent restorations, shade-matched resin cement is strongly recommended. Cement shade can visibly affect the final color of thin porcelain restorations.
4. Zinc Phosphate Dental Cement
Zinc phosphate dental cement is one of the oldest luting agents in dentistry. Though it has been largely replaced by newer formulations, it remains clinically relevant for:
Full metal crown cementation where chemical adhesion is not required
High-volume practices where cost and simplicity are paramount
Cases where the restoration's mechanical retention is excellent
Zinc phosphate offers excellent compressive strength and a very thin film thickness when mixed correctly. However, it provides no chemical adhesion and can cause pulpal irritation due to its acidic pH during setting — a limitation that has driven the adoption of glass ionomer and RMGI formulations.
5. Polycarboxylate Cement
Polycarboxylate cement — also known as zinc polycarboxylate — was developed as a more biocompatible alternative to zinc phosphate. It bonds chemically to tooth structure via polyacrylic acid chains and is considered gentle on the pulp.
6. Temporary Dental Cement
Temporary dental cement is formulated to provide secure but retrievable retention for provisional restorations. Temporary luting agents are used during:
Provisional crown placement while the permanent restoration is being fabricated
Diagnostic phases requiring future retrievability
Implant crown restoration where retrievability is clinically planned
Temporary cements are available in eugenol-containing and non-eugenol (ZOE-free) formulations. Non-eugenol versions are preferred when definitive cementation with resin cement is planned, as eugenol residue can inhibit resin polymerization.
How to Choose the Right Dental Cement for Crowns
No single cement is considered to be the best for placing crowns, but it would be that which is well-suited for a particular situation. The five most critical factors in selecting the right dental cement include:
Step 1: Cement Matching to the Restorative Material
All-ceramic crowns/lithium disilicate crowns: Adhesive resin cement(light cure or dual cure)
Feldspathic porcelain veneers: Light-cure resin cement for color accuracy
Zirconia crowns: Resin cement with MDP bonding agent or RMGI cement with sufficient retention
PFM/Metal crowns: RMGI or glass ionomer cement
Retrievable implant crowns: Temporary cement
Permanent implant crowns: Resin cement or RMGI cement
Step 2: Assess Preparation Retention
If the preparation has good dimensions with respect to its height, taper and surface area, RMGI or glass ionomer cement will provide enough retention. Where there is poor retention of the preparation (short clinical crown, over-tapered preparation), adhesive resin cement becomes important to balance the deficiencies by chemical bonding.
Step 3: Assess Isolation of Preparation
Since resin cement requires proper isolation while being placed, contamination by saliva or blood weakens the bond created by the cement. In situations where there are subgingival margins or lack of adequate field of view, RMGI or glass ionomer cement, which are more tolerant of moisture, should be used than adhesive resin cement.
Step 4: Check Esthetic Demand
In the case of translucent restorations, color-matching of the cement becomes an issue. Where esthetics are critical in the region, the restoration will need a resin cement whose shade matches that of the tooth. For PFM or metal restorations, where shade of cement does not matter, the best option is GIC or RMGI.
Step 5: Assess Retrievability
Any restoration that needs to be accessed in the future should receive temporary cement, which is used for provisionals and implants. Restorations that do not require retrievability should be permanently cemented.
Permanent vs Temporary Dental Cement: Key Differences
One of the most frequent queries put forward by both dentists and patients alike is: "What is the difference between permanent and temporary dental cement?"
Permanent dental cement is made specifically for providing long-lasting retention during the whole period of existence of the restoration. Such a type of cement ensures permanent attachment to the tooth tissue and internal walls of the restoration itself. After setting, it cannot be dissolved by any oral liquid or physical action; it can only be removed professionally.
Temporary dental cement is used only for temporary retention of a provisional restoration, which allows easy retrieval of the restoration at a later time. Temporary cements have a low level of adhesion on purpose.
The use of temporary dental cement instead of permanent cementation may result in a number of problems.
Essential Tools for Accurate Dental Cement Mixing
No matter which dental cement is selected, accurate mixing is critical to achieving optimal film thickness, working time and bond strength. Poorly mixed cement — whether undermixed or overmixed — compromises all of these properties.
The following instruments are considered essential for precise cement preparation:
Precision Dental Material Mixing Spatula – C-24 — Designed for consistent hand-mix cement preparation with ergonomic handling.
Flexible Cement Spatula – C-24 — The flexible blade allows thorough incorporation of powder into liquid, reducing the risk of unmixed pockets.
Double-Ended Cement Spatula — Two working ends allow both mixing and placement without instrument changes, streamlining workflow.
Proper spatulation technique on a cool, dry glass slab — incorporating the powder gradually into the liquid using broad sweeping strokes — produces a cement mix with optimal film thickness and working time. Film thickness below 25 microns is the target for most permanent crown cements.
Frequently Asked Questions About Dental Cement
What is dental cement?
Dental cement is a luting agent that serves as a bond between restorations like crowns, bridges, inlays, onlays and orthodontic bands and natural teeth or implant abutments. Retention could either be mechanical, chemical, or both based on the composition of the cement.
How long does dental cement last?
The longevity of dental cement will greatly depend on the type of cement and the circumstances of its application:
Permanent Dental Cement (resin, RMGI): Should last as long as the life span of the restoration, which could range from 10 to 20 years or even more with good oral care and management of the bite pressure.
Glass Ionomer Cement: Very tough and durable in a stress-free environment; thus, it is generally regarded as an appropriate choice for long-lasting cementation in any non-aesthetic case.
Temporary Dental Cement: Intended to last for several weeks to months. Unsuitable for long-term use.
Loosening or dislodgement of the dental restoration cemented by dental cement is possible due to reasons like contamination of the cement when applied, poor retention of the preparation, occlusal trauma, or habits like grinding the teeth.
How is Dental Cement Removed?
The method of removing cement depends on whether the substance used is temporary or permanent:
Temporary cement: Removal done mechanically using hand instruments, curettes, or crown and bridge removers. Formulated to detach with less effort and force.
Permanent resin cement: Removal by instrumentation performed only by a professional; uses rotary burs, ultrasonic scalers, or crown removers. In some instances, sectioning of the restoration becomes necessary for its removal.
Glass ionomer cement: Removal by ultrasound scaling and mechanical instrumentation; generally easier to remove compared to adhesive resin cement.
It is highly recommended that one does not attempt at home the removal of any type of dental cement. This procedure can result in breakage of the tooth, damage to other teeth, or swallowing of the restoration.
Which is the Strongest Dental Cement for Permanent Crowns?
Adhesive resin cements including self-adhesive varieties provide a stronger bond than other types of luting agents presently available. The answer "the strongest" is not necessarily the best in all situations. There are certain situations where RMGI performs better clinically despite having lower bond strength when compared to adhesive resin cement because of the forgiving nature of the former.
Final Thoughts: Choosing the Best Dental Cement for Crowns
The decision should be made according to clinical factors, material compatibility and long-term objectives.
Contemporary dental cements include resins and RMGI, which offer outstanding results, whereas the traditional dental cements, such as zinc phosphate cement, have practical applications. When differentiating between permanent and temporary dental cement, dentists are able to ensure optimal retention and minimize complications.
An informed selection of dental cements guarantees effective restoration treatment.
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