In recent years there is a rapid increase in the use of computer aided design and production. Two main types of materials are used in the production of indirect CAD/CAM restorations namely resin composite based and ceramic ones. Mechanical properties and esthetics of ceramic materials are superior to resin composites but the advantages of intraoral repair, easy adjustments and polish of resin materials are undeniable. Improvements of mechanical properties of resin-based materials resulted in the development of resin composite blocks.

3D printed restorations, which can be performed as chairside in one session can be manufactured in case of any broken / chipping / debonding cases, without the need for repeated impression making. This saves time for the patient and the clinician. By using these 3D resin-based composite materials in fixed partial dentures, intraoral repairs can be performed. In addition, the high costs of burs and possible damage to the CAD/CAM blocks used in ceramic milling are eliminated when restoration are manufactured in printers with the DLP technology.

The objective of this study was to evaluate the clinical outcome of 3D printed posterior resin composite FDP restorations up to 3 years.

The study will be carried out as a prospective study, with assessment of the restorations after three year. The project includes 3-unit posterior fixed dental prosthesis (FDP) for 70 cases.

Patients participating in the investigation are going to be informed by the "Clinicians" on the background and risk of the investigation. Patients have to give their written consent to participate in the investigation.

The treatment procedure includes the following steps:

Preparation scanning, colour determination, design of the restoration, printing the restoration, adjusting occlusion, finishing and polishing and cementation of the FDP.

The control procedures:

Two weeks after cementation, baseline control will be performed according to USPHS and FDI 2. The restorations will be evaluated at 3 years recall.

Inclusion Criteria:

• Need for a three-unit posterior FDP
• One missing tooth from the second premolar to the second molar where 1st molar is missing (pontic replacing 1st molar)
• Presence of opposing natural dentition (either intact or restored with intracoronal or extracoronal fixed restorations), and with a minimum of 20 teeth)
• Only FPD s with end abutments (No cantilever)
• Sufficient length of the clinical crown (>5 mm)
• No obvious untreated caries, dental health problems (regularly checked by a dentist)
• Good or moderate oral hygiene (plaque score of less than 30% in anterior region be-fore treatment)
• No untreated periodontal disease (only DPSI 1, 2)
• Abutment teeth are vital or endodontically treated with a sealed root filling to the apical region, and have to be without apical periodontitis for the past 6 months.
• Subjects had to be over the age of 18, be classified according to the American Society of Anesthesiologists (ASA) as ASA I or ASA II, present with good oral hygiene, and be free of periodontal disease (probing depth and attachment levels within normal limits, no furcation involvement, and no mobility)
• Subjects had to agree to keep the scheduled recall appointments for data collection and maintenance and plan to stay in the area for at least 3 years.

Exclusion Criteria:

• Patients suffering from general health impairment
• Considerable horizontal and/or vertical mobility of teeth: tooth mobility index score 2 or - Considerable periodontal disease without treatment (DPSI 3-, 3+ and 4)
• Endodontic treatment with extensive loss of tooth tissue
• Subjects who presented with severe wear facets and/or reported parafunctional activi-ties such as clenching or nocturnal bruxism
• Subjects who were restored with a removable partial dental prosthesis (RPDP), unless the RPDP replaced the tooth that was planned to be restored in the study
• Subjects who were pregnant during the duration of the study
• Subjects who are known to be allergic to the ingredients of resin materials