Occlusal Adjustment Time and Volume for Single Unit Fixed Prosthesis Fabricated With Different Virtual Mounting

Regardless of the fabrication workflow occlusal adjustments seem to be inevitable during delivery of indirect fabrication of the restoration. This has been attributed to snowballing of discrepancies due to multiple procedures for information transfer between the clinician and the laboratory. Current digital workflows minimize these discrepancies due to digital acquisition technology which eliminates drawbacks from physical materials which would alter the dimensions and morphology of the final restoration. Utilizing 3D face scanning technology is by far the least invasive and the least time consuming of available virtual facebow techniques and thus it's utilization could offer the benefit of saving time during occlusal adjustment and enhanced strength of the restoration by not subjecting it to the heat generation and subsequent crack initiation which occurs during occlusal adjustment. This study aims to compare the effect of a face scan to alignment of the maxillary cast on the volume and time of occlusal adjustment compared to conventional articulator digitization to align the maxillary cast.

This study will be carried out on participants enrolled at the outpatient fixed prosthodontics clinic, Faculty of Dentistry, Cairo University.

Digital face scanning technology has made it possible to align the maxillary cast in a virtual articulator to represent a more accurate relationship to the terminal hinge axis of the patient than average positioning on a virtual Bonwill triangle. This would be reflected on the occlusal design of the restoration and subsequently on the amount of adjustment needed to the occlusal surface of the restoration during delivery. Decreasing the amount and time of occlusal adjustment would result in a decrease in chair time, increase in the longevity of the restoration and enhanced esthetics of the restoration.

Conventional alignment and mounting of casts to simulate the patients' dynamic occlusions remains the gold standard to which newer digital cast alignment and relation technology is to be compared. Thus the selection of the articulator scan as the comparator was made

Participants' Timeline

Clinical Visit 1 Preoperative records Clinical examination, Radiographic examination, Assessment of inclusion, Informed consent, Intraoral photographs, Primary impression (irreversible hydrocolloid) for diagnostic cast fabrication.

Clinical Visit 2 Facebow record, Articulator mounting, Face Scan, Foundation restoration for participant tooth built to full contour.

Clinical Visit 3 Preparation, Impression, Provisionalisation,

Allocation Impartial third party randomly allocates jaw relation methods to participants and informs laboratory technician of allocation results.

Single unit fixed prosthesis will be fabricated as per allocation results

Clinical Visit 4 Checking and verification of restoration ensuring

1. Proximal contour and contact.
2. Marginal integrity
3. Facial and lingual contours.
4. Surface finish.
5. Color and shade.

Impression prior to occlusal adjustment, Occlusal adjustment, Timing occlusal adjustment procedure, Impression after occlusal adjustment, Cementation.

Eligibility Criteria:
Inclusion Criteria:

* Be aged 21-70 years old, be able to read and sign the informed consent document.
* Psychologically and physically able to withstand conventional dental procedures.
* Participants with molars indicated for full coverage restorations

  1. Large carious lesions
  2. Teeth restored with large restorations
  3. Endodontically treated teeth
* Accept to undergo face scanning and articulator mounting procedures
* Have no active periodontal or pulpal diseases, have teeth with clinically acceptable restorations.
* Able to attend punctually for preplanned visits and evaluation.

Exclusion Criteria:

* Participants with active resistant periodontal diseases.
* Participants with poor oral hygiene, high caries risk and uncooperative participants.
* Pregnant women.
* Participants in the growth stage with partially erupted teeth.
* Psychiatric problems or unrealistic expectations.
* Lack of opposing dentition in the area of interest.
* Restored occlusal surface opposing the planned restoration.
* The presence of a removable or fixed orthodontic appliance.
* Signs of bruxism or clenching