The Low Window Technique: Comparison between Manual and CAD/CAM-guided Design

Area of Science:

• Oral and Maxillofacial Surgery
• Dental Implantology
• Computer-Aided Design and Manufacturing (CAD/CAM)

Background:

• Sinus augmentation is crucial for dental implant placement in the posterior maxilla.
• The low window technique for sinus augmentation has potential benefits but requires precise execution.
• Manual design of the surgical access window can be subject to variability and inaccuracies.

Purpose of the Study:

• To quantitatively compare the accuracy and reproducibility of manual low window designs versus computer-aided design and computer-aided manufacturing (CAD/CAM)-guided designs for sinus augmentation.
• To assess the inter-operator variability in designing surgical access windows.

Main Methods:

• Five stereolithographic models were 3D-printed from cone-beam computed tomography (CBCT) scans of partially edentulous maxillae.
• Five experienced maxillofacial surgeons designed low and high window access for sinus augmentation on the models, both manually and using CAD/CAM surgical guides.
• Accuracy and inter-operator variability of the designs were analyzed.

Main Results:

• Manual low window designs exhibited clinically significant deviations in shape, size, and positioning compared to CAD/CAM-guided designs.
• Placement errors averaged approximately 3 mm in all directions (apical, coronal, mesial, distal) for manual designs.
• Both intra- and inter-operator variability were low and not significantly influenced by the operator, but manual designs showed greater discrepancies.

Conclusions:

• The compromised accuracy and reproducibility of manual low window designs may limit the technique's advantages.
• Computer-guided approaches are preferred over manual methods for low window sinus lifts to minimize complications and patient discomfort.
• CAD/CAM-guided design is recommended for low window sinus lifts to reduce discrepancies and improve outcomes, especially for less experienced surgeons.