Dental materials play a vital role in ensuring the effectiveness, safety, and longevity of dental procedures. Among these, dental cements and Polycarboxylate Temporary Base (PTB) are essential components used in both temporary and permanent restorations. In the UK, the selection and application of these materials are governed by clinical efficacy, patient safety, and compliance with strict regulatory standards like those of the MHRA (Medicines and Healthcare products Regulatory Agency) and UKCA (UK Conformity Assessed) marking post-Brexit.

This article explores the nature of PTB and dental cement, their uses in modern UK dental practices, and the key considerations for their appropriate clinical application.

What is PTB?

PTB stands for Polycarboxylate Temporary Base, a type of temporary restorative material commonly used in dentistry. PTB is designed to provide a temporary seal or base beneath permanent restorations, especially during procedures that require multiple visits or when the pulp needs to be protected.

Composition

PTB typically consists of:

• Zinc oxide powder: Provides the bulk of the material.

• Polyacrylic acid liquid: Acts as the reactive component.

• Additives: May include stannous fluoride for antibacterial properties and radiopacity.

Properties

• Biocompatibility: Gentle on pulp tissue, making it suitable for use near or over exposed dentin.

• Adhesion: Bonds chemically to tooth structure without needing a bonding agent.

• Insulating capacity: Acts as a thermal and electrical barrier between the tooth and restorative materials.

• Ease of use: Can be mixed and placed quickly during chairside procedures.

What is Dental Cement?

Dental cement is a broader category of materials used for luting (cementing), lining, or restoring parts of the tooth. It may be temporary or permanent, and its functions range from securing crowns and bridges to lining cavities or filling them.

Main Types of Dental Cements Used in the UK

1. Zinc Phosphate Cement

   • Oldest type used in dentistry.

   • High compressive strength, but acidic and potentially irritating to the pulp.

2. Polycarboxylate Cement

   • Chemically similar to PTB.

   • Bonds to enamel and dentine with minimal pulp irritation.

3. Glass Ionomer Cement (GIC)

   • Releases fluoride.

   • Bonds to tooth structure and is often used for class V restorations and as a base.

4. Resin-Based Cements

   • Used for permanent cementation of inlays, onlays, crowns, and veneers.

   • High bond strength and aesthetic.

5. Temporary Cements

   • Zinc oxide eugenol or non-eugenol based.

   • Easily removed and suitable for temporary restorations or trial crowns.

Clinical Uses of PTB in Dentistry

In a UK clinical setting, PTB is widely used in the following applications:

1. Temporary Filling Material

   • Used between endodontic appointments or when a tooth requires further monitoring.

   • Maintains occlusion and protects against food impaction or bacterial contamination.

2. Base Material

   • Placed under amalgam or composite to protect the pulp and reduce post-operative sensitivity.

3. Liner

   • Functions as a protective barrier for the dentin, especially in deep cavities.

4. Pulp Protection

   • Owing to its biocompatibility, it is used in procedures where there is a risk of pulp exposure.

Benefits of PTB and Dental Cements in UK Practice

1. Pulpal Protection

Both PTB and polycarboxylate cement are known for their gentle effect on pulp tissue, which is crucial for avoiding pulpal necrosis and sensitivity post-procedure.

2. Ease of Manipulation

Materials like PTB have manageable setting times, can be applied quickly, and do not require extensive equipment—perfect for NHS and private practices alike.

3. Chemical Adhesion

Unlike resin cements that require etching and bonding agents, PTB and polycarboxylate cement adhere directly to enamel and dentine.

4. Regulatory Approval

Most dental cements available in the UK carry UKCA or CE markings, ensuring their safety and efficacy under British regulations.

Limitations and Considerations

1. Limited Aesthetic Properties

PTB is typically white or off-white, lacking the translucency and polishability required for anterior restorations.

2. Lower Mechanical Strength

Compared to permanent resin-based cements, PTB and basic zinc-based cements are weaker and prone to wear, making them unsuitable for long-term load-bearing applications.

3. Moisture Sensitivity

Some cements are sensitive to moisture during setting, which may compromise their final properties. Proper isolation is crucial.

4. Temporary Use Only

As the name suggests, PTB is not intended for long-term restorations. It should be replaced with a more durable material in due course.

Regulatory Considerations in the UK

Following the UK's exit from the EU, medical and dental devices, including cements, are regulated under the UK Medical Devices Regulations 2002, with amendments post-Brexit. Key points include:

UKCA Marking

• Replaces the CE mark for products marketed in Great Britain.

• Dental cements must carry this mark to be legally sold.

• Indicates conformity with safety, clinical efficacy, and quality standards.

MHRA Oversight

• The Medicines and Healthcare products Regulatory Agency oversees dental material safety.

• Reports of adverse events or reactions to dental cements are monitored and can lead to product recalls or advisories.

Infection Control

• Dental materials used in UK clinics must meet HTM 01-05 decontamination standards and be traceable in case of cross-contamination issues.

Best Practices for UK Dental Practitioners

1. Material Selection

   • Choose the right cement based on the procedure. PTB for temporary fillings, resin-based for permanent crowns.

2. Patient Communication

   • Inform patients when a temporary material like PTB is used, and schedule timely follow-ups for definitive restorations.

3. Compliance

   • Ensure all materials used are UKCA/CE-marked and from reputable suppliers.

4. Training and CPD

   • Dentists and dental nurses should stay updated through CPD (Continuing Professional Development) on new materials, application techniques, and regulatory changes.

Future Trends

Innovations in dental cements continue, including:

• Bioactive cements that promote remineralisation.

• Antibacterial cements incorporating silver or chlorhexidine.

• Dual-cure systems for better control and strength in deep restorations.

PTB-type materials are also evolving, with improved compressive strength and better aesthetics for extended temporary use.