# Comparative Evaluation of the Wear Rate of Reinforced Glass Ionomer Cement and Bulk-Fill Composite Using 3D Scan in Extracted Teeth and Its Association With Clinical Wear Rate in Class I and II Restorations: A Randomized Clinical Trial

## TL;DR

This study compares the wear resistance of reinforced glass ionomer cement and bulk-fill composite in dental restorations using a standardized in vitro and clinical protocol.

## Contribution

A standardized protocol was developed to evaluate and correlate in vitro and clinical wear resistance of reinforced GIC and bulk-fill composites in posterior restorations.

## Key findings

- The in vitro wear resistance of reinforced GIC and bulk-fill composites was evaluated using a chewing simulator and 3D scanning.
- Clinical wear was monitored using 3D models and FDI criteria to assess long-term performance in patients.
- The protocol successfully correlated simulated wear with clinical observations in Class I and II restorations.

## Abstract

Background: Reinforced glass ionomer cements (GICs) have gained attention as potential durable alternatives to resin composites for posterior restorations, owing to their improved mechanical properties and fluoride release. However, limited standardized protocols exist to assess their long-term wear resistance and clinical performance, particularly in comparison with bulk-fill resin composites under variable patient-related factors.

Aim: This study aimed to develop a standardized protocol to evaluate the suitability of reinforced GIC as a durable permanent direct restorative material in Class I and Class II cavities compared with bulk-fill resin composites and to correlate in vitro findings with clinical wear behavior.

Materials and methods: The study consisted of two phases: an in vitro experimental phase followed by a correlational clinical trial. In the in vitro phase, 40 extracted human molar teeth were collected and divided according to cavity type: Group 1 (Class I cavities; n = 20), Group 2 (Class II cavities; n = 20), and subgroups a (reinforced GIC; n = 10) and b (bulk-fill composite; n = 10). The restored samples were stored in distilled water for 24 hours and subjected to simulated mastication cycles equivalent to six and 12 months of clinical function using a chewing simulator. Volumetric wear was determined using the Geomagic software (3D Systems, Rock Hill, SC, USA). In the clinical phase, restorations made of the same materials and with the same cavity configurations were placed in patients and monitored periodically for three-dimensional wear and volumetric changes.

Results: The wear was assessed using the Geomagic Control X (3D Systems, Rock Hill, SC, USA) and WearCompare software on replica models, and restorations were analyzed using the revised Fédération Dentaire Internationale (FDI) criteria.

Conclusion: The standardized in vitro-in vivo protocol provides a reliable framework to assess the durability and clinical relevance of reinforced GICs compared with bulk-fill composites in posterior restorations, offering insight into their long-term functional behavior under patient-related influences.