Basic Study of Fabricating Biomorphic Crowns
Condition: Dental Crown; Prosthesis
Study type: Interventional

Summary: 
      The purpose of this study is to compare among different designs of the occlusal surface of
      artificial crowns, trying to determine a guidance of fabricating artificial crowns with
      better mimesis of the original tooth crown in terms of morphology.
    

Detailed description: 
      For occlusal surface design, each subject would be given 3 crowns using different fabricating
      guidance -- the FGP technique(FGP),the average setting technique(AVR) and conventional
      technique(CON), separately. Upon baseline visit, general tooth preparation procedures would
      be performed, including impression taking before and after treatment and tooth preparation.
      Sometimes photo taking is needed. On try-in visit, subjects would be ask to fill in
      questionaires(Likert's scale) and the adjusting time for each crown would be recorded.
      Moreover, t-scan would be used to assess the occlusal equilibrium. All in all, including
      adjusting visit for FGP, the subjects have to visit the clinic for 3 times which would take
      them 3-week time.

      The Institutional Board(IRB) of the Stomatological Hospital of Fourth Military Medical
      University(FMMU) would be in supervision of the whole study and is responsible for the
      quality assurance plan, data check and source data verification.

      Subject recruitment would done within those patients visit the department of prosthodontics
      of the Stomatological Hospital of FMMU and have an interest towards this study. One clinician
      would be appointed to enroll the subjects according to the standards. To avoid errors, all
      the examinations done in the study shall be accomplished by the same clinician and the crowns
      fabricated in the study shall be designed by the same technician. The clinician and the
      technician participated would receive adequate training before the study to ensure their
      performance. Every subject in the study should assign informed consents at the beginning of
      the study and establish case report forms(CRFs). During the study, if adverse events(such as
      crown chipping, crown dropping or iatrogenic gingivitis, etc) happen, subjects are required
      to contact the investigator within 24 hours; and the investigator should then report to the
      IRB within 24 hours. Following treatment or compensation would be done according to the
      clauses stated in the informed consent signed by the subjects.

      The whole study needs subjects in total. During the study, subjects have their own right to
      quit the study at any time if they have discussed with the investigator in advance. These
      subjects then are deemed as "unavailable". If subjects don't contact the investigator and
      quit the study(the investigators can't contact them within the follow-up period), their
      records then are deemed as "missing".

      All the information collected in the study would be protected and only be used within this
      study. The statistical analysis of this study would be processed with the aid of the
      department of statistics of FMMU.
    

Intervention name(s): FGP; AVR
Intervention type(s): Procedure; Procedure
Intervention description(s): To execute FGP technique, the occlusal surface of the interim should be back cut to leave at least 1mm occlusal space. Then apply the recording resin. Ask the subjects to close the mouth to maximum intercuspal position then perform right lateral, left lateral and protrusive movements in succession ending in maximum intercuspation position. Excessive resin then should be trimmed off and Bausch articulating paper would be used to mark the intercuspal contacts. Zinc oxide is then applied to check eccentric occlusion, trimmed off resin if there're interferences. Then the interim would be used as a copy to design the occlusal surface of the crown. (CAD/CAM); the crowns in this group would be designed by setting virtual articulator to average mode (CAD/CAM)
Other intervention name(s): general; average value
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: artificial crown; biomorphic; functional generated path; muscle-action theory; anatomic theory