Longevity of Dental Fillings by Chairside Technique Utilizing 3D Printing vs. Direct Composite Fillings

Introduction

In dentistry, filling materials are needed repairing damage caused by dental caries as well as for occlusal rehabilitation. Composite restorations can be performed using direct or indirect technique. There are some shortcomings linked with direct technique, such as polymerization shrinkage, and also their manufacturing can be demanding due to circumstances in the oral cavity. Partly due to these, approximately 8 out 10 regular users of dental services need repetitive repair or replacement of old restorations within 5 years. One solution for manufacturing high-qualified and long-lasting restorations is chairside CAD/CAM (computer-aided design and computer-aided manufacturing) technology that includes both subtractive and additive manufacturing techniques. Additive techniques, also called 3D printing techniques, may provide novel possibilities to overcome the challenges linked with the durability of dental fillings. They might be used to fabricate more complex restorations compared to subtractive techniques with a reasonable cost. In 3D printing, successive layers of material are deposited under computer control to create an object layer by layer. The objects, having practically any shape or geometry, are produced from a model or design in an electronic form. The 3D printable models may be created with a CAD software package and in many cases utilize the imaging data by a dental scanner which have become widely available with high resolution. 3D printing may enable higher restoration accuracy compared to subtractive manufacturing techniques, where the accuracy is limited by the milling unit and machining tools. Another benefit is its low material loss. 3D printing process is fast and likely in future to be used chairside at the dental office. Only a few studies addressing the possibilities of 3D printing in dental filling manufacture exist in the current literature. Based on a previous in vitro study by the imvestigators, the accuracy of 3D printing technique is at least at the same level as milling technique in fabrication of dental inlay and onlay fillings, and thus might be a clinically acceptable alternative to the subtractive milling technique. Additional clinical investigations are needed to confirm these findings. The aim of the present study is to compare the success of dental fillings prepared using 3D printing technique to those manufactured with the direct composite technique.

Material and Methods

At total, 100 adult patients are selected from dental care patients of the Health Centre of Kaarina, Kaarina, Finland, as volunteers. Written informed consent forms are obtained from all patients at the beginning of the study. Participation in the study is voluntary and causes no additional costs for the patient.

Each patient requires two Class II, III or IV cavities to be restored in the dentition. The randomizations are performed by noting each tooth to be restored (Fédération Dentaire Internationale [FDI] two-digit code) on one form and the type of restorative system (direct technique vs. indirect technique utilizing 3D printing) on a second. First, a tooth number is drawn blindly. Subsequently, a restorative system is allocated to this tooth by blind drawing. The clinical procedures of cavity preparation and restoration placement are performed by two experienced dentists.