Clinical evaluation of the effectiveness of 3 laboratory fabrication methods on marginal adaptation of metal-ceramic single crowns, which are impressed digitally

Clinical evaluation of marginal adaptation of the metal-ceramic single crowns impressed digitally and fabricated by lost wax technique and CAD/CAM with new technology

In this study,60 abutment teeth in need of crown reconstruction that have inclusion criteria and come to Kermanshah dental college were randomly assigned to intervention groups.

Abutment teeth that require crown reconstruction randomly divide into 3 intervention groups.After impressing digitally and preparing tooth by the dentist specialist, the restoration of each group is made in the laboratory. This restorations are examined before and after vinylation with 3 techniques for marginal adaptation:1-Parallel bite wing radiography 2-Touching the margins of crown using sonde 3-Silicone replica technique:In this technique, after molding the space between the crown and abutment tooth using silicone, the specimens are measured under a Stereomicroscope. In this triple blind study, patients and researchers and evaluator and laboratorist do not know the details of the study and the method of randomization.

INCLUSION:1- Good general health 2- Periodontal health 3-No obvious sign or symptom of bruxism and/or clenching 4-Abutment requires reconstruction 5-Non-vital abutment teeth with positive long-term prognosis 6-Sufficient periodontal support for single crown restoration and minimum mobility 7-Sufficient tooth preparation length to ensure retention and resistance forms 8-Patients should be satisfied to join our study and sign the consent EXCLUSION:1-Poor oral hygiene 2-Clinical sign and mobility(grade 2 and more) 3-Parafunctional habits 4-Periodontitis and severe gingivits

1-control group: casting crowns 2- CAD/Milling crowns 3-CAD/Ceramill Sintron crowns

Clinical adaptation

Based on the random allocation rule, after determining 60 maxillary and mandibular first molars based on statistical calculations, 20 cards for the Casting group, 20 cards for the CAD/Milling group, and 20 cards for the CAD/Ceramill Sintron group will be placed in a draw glass, then the cards will be dropped out randomly and without replacement and resulting sequence will be recorded. Then, 60 envelopes are prepared and each random sequence created is recorded on a card and the cards are inserted into the envelope respectively. In order to maintain a random sequence, the envelopes are numbered to the same. In the end, the door covers are enclosed in boxes and placed in a box respectively. At the time of the start of the registration of the participants, according to the order of entry of qualified participants to study, one of the envelopes are opened in sequence and the participant's assigned group is revealed.

In this clinical trial study, the main researchers involved in, the prostodontic and student are blind to the assignment of each participant in each of the study groups. Participants in the study are blind toward their own group while they are aware of the similar costs and benefits of clinical treatments based on studies. Also the result analyst and the outcome evaluator, have no information about the data of each group.The Laboratorist is not also aware of each group assignment. Only a health care worker knows about the groups.