Accuracy and Reproducibility of Virtually Guided Minimally Invasive Tooth Preparations Using Reverse Engineering

Accuracy and Reproducibility of Virtually Guided Minimally Invasive Tooth Preparations Using Reverse Engineering (Controlled Clinical Trial)

The aim of the study is to assess and reproduce standardized virtually guided minimally invasive tooth preparations using digitally designed occlusal template, compared to its reference virtual preparation using a computer aided 3-dimensional (3-D) analysis, and to investigate the effect of these preparations on absolute marginal discrepancy of 3 unit monolithic translucent zirconia FPD using a computer aided 3-D analysis.

Ten patients with missing mandibular first molar will receive a three-unit full contour monolithic zirconia FPD. Each patient case will receive two modes of preparation as in the previous in-vitro study: virtually guided tooth preparation using occlusal resin template to assist the intraoral preparation and the reference virtual tooth preparation. Each participant's preparation will be evaluated using diagnostic dental software and will be compared to a reference digital virtual preparation using 3-D mesh processing reverse engineering metrology software.

Inclusion Criteria:

• Patients with a missing lower first mandibular molar.
• Good oral hygiene with no signs of periapical pathology or periodontal disease (periodontal screening index 0-1) and with compliance to perform strict oral hygiene measures.
• Well-aligned abutment teeth with similar mesio-distal (M-D) and bucco-lingual (B- L) dimensions; (2nd premolar: M-D 7.8 mm ±1, B-L 8.7 mm ±1), (2nd molar: M-D 10.73±1, B-L 10.5 mm ±1).
• Abutment teeth with an adequate occluso-gingival height where (2nd premolar: 8.4 mm ±1, 2nd molar 7mm ±1), and adequate edentulous span length (9.5 mm±1); for an appropriate connector area of at least 9 mm.
• Absence of parafunctional habits (clinching, bruxism).

Exclusion Criteria:

• Bad oral hygiene.
• Advanced periodontitis, gingivitis, or recession.
• Abutments with subgingival restorations, root caries.
• Parafunctional habits.
• Undergoing orthodontic treatment.
• Obvious dentition malalignment.