RESUMEN
This clinical report introduces an approach for detecting the supragingival finish line by penetrating the teeth and gingival tissue using optical coherence tomography (OCT) technology. This approach was used in 3 patients who underwent tooth preparation with a subgingival finish line. Consequently, the subgingival finish line, typically challenging to discern clearly in intraoral scans, was identifiable in the OCT image.
RESUMEN
OBJECTIVES: This study aimed to evaluate the marginal and internal fit of zirconia crowns were fabricated using scan data from an intraoral optical coherence tomography (OCT) scanner and an intraoral scanner (IOS) for scanning the subgingival finish line. METHODS: An extracted maxillary left central incisor was prepared for a zirconia crown. The prepared tooth was placed in artificial gingiva, created using silicone with a refractive index similar to that of the tooth, ensuring a subgingival depth of 0.50 to 0.70 mm from the labial finish line. Scanning data were obtained from four types of models as follows. (1) CAD reference model (CRM) excluding the gingiva and scanned using a laboratory scanner. (2) IOS group excluding the gingiva (IOS only, IOSO group). (3) IOS group with scanned attached artificial (IOS with gingiva, IOSG group). (4) OCT post-processed data of the subgingival finish line and IOSG data (OCT group). Zirconia crowns were fabricated based on these data, and their marginal and internal fit were evaluated using the silicone replica technique. Statistical analyses were conducted using one-way and two-way ANOVA (α = 0.05). RESULTS: The OCT group exhibited a significantly smaller marginal gap than the IOSG group (P < 0.05). The marginal fit of the OCT group did not significantly differ from that of the CRM group (P > 0.05). The IOSG group exhibited a significantly larger chamfer gap, while both the IOSG and OCT groups had significantly larger axial gaps. Furthermore, the OCT group showed a significantly larger incisal gap (P < 0.05). CONCLUSIONS: An intraoral OCT system can enhance the fabrication accuracy of zirconia crowns by achieving superior marginal fit for crowns with subgingival finish lines. CLINICAL SIGNIFICANCE: The use of an IOS for subgingival finish lines without gingival displacement cords may result in a suboptimal marginal fit. However, integrating OCT technology can effectively address this issue, leading to improved clinical outcomes.
RESUMEN
PATIENTS: The patient was a 32-year-old man who underwent amalgam restoration of the mandibular right second molar. An amalgam restoration fracture was diagnosed by intraoral optical coherence tomography (OCT), and pulp exposure was examined during cavity preparation. Subsequently, a definitive ceramic restoration was fabricated, and the marginal fit in the oral cavity was evaluated using the OCT system. DISCUSSION: The existing OCT system cannot acquire images inside the oral cavity because of the large probe size. However, the proposed intraoral OCT system can access the prostheses in the mandibular right second molar. Therefore, dental diagnosis for restoration treatment with dental prosthesis fracture, marginal gap, and pulp exposure after tooth preparation is possible using the proposed intraoral OCT system. CONCLUSIONS: The use of the intraoral OCT system improved dental diagnosis by allowing the dentist to confirm quantitative values through cross-sectional images, rather than that by determining a treatment plan after visual dental diagnosis.