Aslı Çiftçi

The accuracy of full-arch digital impressions remains a topic of debate despite advancements in intraoral scanning technologies. This in vitro study aimed to evaluate the effect of different intraoral scanner generations (TRIOS 3, TRIOS 5, and TRIOS 6) on full-arch digital impression accuracy by comparing dentate and fully prepared models. A dentate and a fully prepared maxillary model were digitized using a high-accuracy desktop scanner to create reference datasets. The models were fabricated with a 3D printer, and a total of 60 digital impressions were obtained, with 10 repeated scans for each scanner–model combination. Accuracy was assessed by comparing STL datasets with the reference models using root mean square (RMS) deviation values. The results showed that TRIOS 3 and TRIOS 5 demonstrated similar accuracy performance across both model types, whereas TRIOS 6 exhibited higher deviation values, particularly in the fully prepared model. Furthermore, model type had a significant effect on accuracy, and a statistically significant interaction was observed between scanner type and model type. These findings indicate that digital impression accuracy is influenced not only by scanner generation but also by surface morphology and reference characteristics.

The durability of bonding between the denture base and reline materials plays a critical role in the long-term success of removable prostheses. This study aimed to compare the bond strength of denture base resins fabricated by heat-polymerization, CAD-CAM milling, and 3D printing techniques after thermocycling and different surface treatments. A total of 216 specimens (10 × 10 × 20 mm) were prepared from three base materials and subjected to surface treatment via no treatment (control), alumina air abrasion, or an Er/YAG laser. Two reline materials (hard and soft) were applied according to manufacturers’ instructions. All samples underwent 5000 thermal cycles and were tested using a tensile bond strength test. SEM analysis was performed to evaluate failure modes. The highest bond strength was observed in the milled resin group combined with alumina air abrasion and the hard reline material, reaching up to 12.41 MPa. Statistically significant effects were found for the material type, surface treatment, and reline material (p < 0.001). The results indicate that material properties, surface preparation, and reline type critically influence bond performance. Milled PMMA bases and hard relining agents, particularly when combined with air abrasion, offer superior bonding outcomes.

Aim: The aim of this study was to observe the change in the surface roughness of composite samples produced by different production methods after sandblasting with aluminum oxide particles and to evaluate the effect of this on the composite material. Methodology: The study tested three subtractive method composites (GC Cerasmart [GC], Vita Enamic [VE] and Grandio Voco [GV]) and one additive method composite (3D Formlabs [3D]) were used. Each subtractive composite had 11 samples (14 x 14 x 2 mm) prepared with an Isomet low-speed saw, whereas the additive composite had 11 specimens produced using an SLA-based 3D printer (Form 2; Formlabs Inc). For roughness measurements and sandblasting, the samples were marked with an adhesive circular paper. Surface roughness was measured using a MarSurf SF1 profilometer, with three readings per sample. Sandblasting with aluminum oxide particles (50 µm) was performed using an Aquacare twin in-mouth sandblaster, and surface roughness measurements were repeated. Statistical analysis was performed using one-way analysis of variance (ANOVA) via SPSS 26, with significance set at p=0.05. Results: Among the composite samples, Vita Enamic (VE) had the highest average roughness value, and 3D Formlabs (3D) had the lowest. VE had a mean roughness value of 0.4575 µm, GC had a mean roughness value of 0.4627 µm, GV had a mean roughness value of 0.665 µm and D had a mean roughness value of 0.4575 µm. All groups were compared pairwise with each other. A significant difference was found between the GV-D, VE-D, GC-GV, GC-VE, and GC-D group pairings (p0.05). Conclusion: Sandblasting with aluminum oxide was observed to increase the roughness of the materials, and the roughness varied depending on the nature of the material. Further studies are required to investigate the effects of roughness on the bonding. How to cite this article: Güntekin N, Alkurt S, Çiftçi A, Gönder HY, Büyükerkmen EB. Evaluation of surface roughness of composites obtained by additive and subtractive manufacturing methods after sandblasting. Int Dent Res. 2024;14(S1):60-64 https://doi.org/10.5577/indentres.559

Objective: This study investigated how the number of images collected for digital measurements in dentistry affects accuracy compared with traditional methods. Methods: A Frasaco maxillary model was scanned using a SHINING 3D AutoScan-DS-MIX dental 3D scanner to create an STL file. The maxilla was molded 10 times using polyvinyl siloxane (Zhermack Elite HD+) to produce plaster models, which were scanned with the same reference scanner to generate 10 STL files. The Frasaco model was scanned 10 times, capturing images in intervals of 800–1000, 1000–1200, and 1200–1500 using a 3Shape TRIOS 3 intraoral scanner, creating additional STL files. These were analyzed with reverse engineering software. Results: The most accurate measurements were obtained using 1200–1500 images. Conventional impression techniques performed significantly worse. There was a significant difference between the groups Digital 1200–1500 and Plaster (p < 0.001) and between Digital 800–1000 and Plaster (p = 0.007). No significant difference was found when the digital groups were compared among themselves. There was also no significant difference between the Plaster and Digital 1000–1200 groups. To compare precision values that were normally distributed across three or more methods, a one-way ANOVA was used. Trueness values that were not normally distributed with three or more methods were compared employing the Kruskal–Wallis test. Conclusions: Different image counts affect digital measurement accuracy. The most accurate measurements were obtained when collecting 1200–1500 images. Conventional impression techniques were shown to perform significantly worse than digital impression.