The Impact of Adhesion Strategy on the Clinical Performance Of Indirect Dental Restorations

The Influence of Cement Systems on the Outcome of Tooth Supported Zirconia Crowns in the Posterior Region: a Randomized ,Multicenter, and Practice-based Clinical Trial

The goal of this clinical trial is to evaluate whether different cement systems influence the clinical outcome of posterior tooth supported zirconia crowns in adult patients requiring single crown restorations. The main questions it aims to answer are:

• Do glass ionomer cements provide clinical outcomes comparable to those of resin cements for posterior zirconia crowns?
• Do marginal discoloration, marginal integrity, and biological complications differ between the cement systems?
• Do patient reported and clinician reported outcomes differ between the cementation procedures?

Researchers will compare zirconia crowns cemented with either a glass ionomer cement or a resin cement to evaluate differences in clinical outcomes.

Participants will:

• Receive posterior zirconia crowns fabricated according to standardized clinical procedures
• Be randomized to cementation with either a glass ionomer cement or a resin cement
• Undergo clinical examinations assessing crown survival, marginal adaptation, discoloration, caries, periodontal status, and wear
• Complete questionnaires regarding patient comfort and treatment experience
• Attend baseline and annual follow-up examinations for up to 10 years

Tooth damage has significant impact on a person's quality of life and damaged teeth should be treated to restore lost functions and prevent further damage. Loss of tooth substance can be restored by a direct (filling) or indirect restoration (artificial crown). These interventions differ in some operative aspects but share key challenges, particularly in achieving optimal adhesion to tooth substance to secure predictable retention and the integrity of the marginal seal.

Failure of the adhesive interface is a major determinant of restoration longevity and may manifest across patient-centered, biological, and technical outcomes.

Marginal degradation may result in discoloration, representing an early clinical indicator of interface breakdown that negatively affects patient satisfaction and may lead to a need for retreatment. Progressive marginal leakage facilitates bacterial access, increasing the risk of biological complications such as secondary caries and pulpal involvement.

Loss of retention represents a major technical complication, often requiring replacement of the restoration and contributing to cumulative loss of tooth structure over time.

Despite advances in restorative materials and adhesive systems, clinical outcomes remain variable, and the relative contribution of material properties, procedural complexity, and biological factors to long-term failure is not fully understood. In particular, the role of technique sensitivity and procedural complexity as independent determinants of restoration survival remains insufficiently characterized. Improved understanding of these interacting factors will enable more precise selection of restorative materials and cementation strategies.

This project will: (a) identify and quantify clinically relevant determinants of restoration failure, enabling improved prediction of restoration survival and patient satisfaction, (b) elucidate how interfacial degradation and technique sensitivity contribute to biological and technical complications, (c) aid clinical decision-making by guiding selection of materials and procedures based on their performance and complexity.

Inclusion Criteria:

• Need of one single crown on vital posterior tooth
• Speak and understand Swedish language
• Free from dental/oral disease; caries, periodontal disease

Exclusion Criteria:

• Only individuals who do not meet the inclusion criteria will be excluded.