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Clinical Implications of Sterilization Methods Applied to 3D-Printed Implant Surgical Guides: An In Vitro Study

2026-04-01T00:00:00Z

Title: Clinical Implications of Sterilization Methods Applied to 3D-Printed Implant Surgical Guides: An In Vitro Study Authors: Go, Hye-Bin; Kim, Gi-Tae; Yu, Jae-Hun; Yoon, Youngjae; Kwon, Jae-Sung Abstract: Introduction and aims: This in vitro study evaluated how 3 sterilization methods-autoclaving, ethylene oxide (EO) gas, and hydrogen peroxide gas plasma-affect the mechanical, physical, and dimensional properties of 3-dimensional (3D) printed implant surgical guides. These techniques are widely used in dental practice but differ in mechanism and limitations. Methods: Twenty specimens were fabricated using a digital light processing printer and divided into 4 groups (n = 5): non-sterilized control, autoclaving (121 degrees C, 15 minutes), EO gas (55 degrees C, 60 minutes), and hydrogen peroxide gas plasma (<57 degrees C, 18 minutes). Mechanical tests evaluated flexural strength, modulus, and Shore D hardness while translucency and dimensional stability were also assessed. Shape deviation and implant positioning accuracy were compared before and after sterilization. Data were analyzed with one-way analysis of variance and Tukey's post hoc test. Results: All sterilized groups maintained internal fit deviations within clinically acceptable tolerance (+/- 120 mu m), showing no significant differences in overall dimensional accuracy. Implant placement precision was preserved, with implant-tooth distances >= 2 mm. EO sterilization significantly increased the flexural strength (122.49 +/- 10.10 MPa) and modulus (3477 +/- 161 MPa) compared with controls whereas autoclaving showed the lowest strength (92.40 +/- 15.06 MPa). Shore D hardness exceeded 90 HS in all groups, with autoclaving producing the highest values. Only EO treatment significantly reduced translucency. Conclusion: Sterilization method influenced the mechanical and optical properties of 3Dprinted surgical guides without compromising dimensional accuracy. (c) 2026 The Authors. Published by Elsevier Inc. on behalf of FDI World Dental Federation. (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Evaluation of blue-light model scanner trueness, precision, and surface detail reproduction with different rubber impression material colors

2026-03-01T00:00:00Z

Title: Evaluation of blue-light model scanner trueness, precision, and surface detail reproduction with different rubber impression material colors Authors: Seo, Kyoungjin; Cai, Hongxin; Shin, Seung-Ho; Choi, Ji-Won; Seo, Young-Bin; Kim, Jong-Eun; Kim, Kwang-Man; Jiang, Heng Bo; Kwon, Jae-Sung Abstract: Objective Although the accuracy of scanning technologies has been extensively explored, a research gap still exists concerning the scanning results of dental impression materials, particularly regarding their color and gloss characteristics. This study aims to evaluate and compare the scanning capabilities of blue-light scanners for various dental impression materials characterized by different colors and gloss levels. Methods Blue (B), green (G), red (R), and yellow (Y) dental impression materials were selected for this study. Colorimetric analyses were conducted using a spectrophotometer. The gloss levels of the samples were quantified using a gloss meter. The accuracy and surface detail reproduction of a blue-light scanner were analyzed by scanning impression materials in four different colors. The four-unit crown-bridge model for accuracy analysis was based on International Standardization Organization (ISO) standard 12836. The data measured by the coordinate measuring machine (CMM) served as the gold standard and were used for parameter comparison (height, angle, and distance) and 3D fitting with the scanned files. Results Surface detail reproduction analyses revealed significant differences among the various groups. Notably, Group B consistently demonstrated superior scanning accuracy across all measurements, indicating its effectiveness as a dental impression material in blue-light scanning applications. Significant differences were observed in the rate of surface detail, angle parameters, and corner height across the various groups (p < 0.05). Additionally, the root-mean-square error values pertaining to trueness exhibited significant disparities in all the specimens (p < 0.05). Significance. The absence of significant gloss differences across all color variations indicates that color should be evaluated alongside other critical factors when employing blue-light scanners for measurement accuracy.

Orthodontic adhesives incorporated with strontium-containing fluorapatite for improved remineralizing effect

2026-03-01T00:00:00Z

Title: Orthodontic adhesives incorporated with strontium-containing fluorapatite for improved remineralizing effect Authors: Hong, Ji-Yeon; Kim, Ji-Eun; Kwon, Jae-Sung Abstract: Objectives This study aimed to develop novel orthodontic adhesives with remineralization effect to prevent white spot lesions (WSLs) by adding strontium-containing fluorapatite (Sr-FAp), fluorapatite (FAp), and strontium-containing hydroxyapatite (Sr-HAp). Methods The particles were synthesized and characterized. The experimental groups consisted of a commercial control (CC), control (30 wt % resin matrix + 70 wt % glass filler), and experimental groups with 17.5 wt % of filler replaced by Sr-FAp, FAp, or Sr-HAp. The brackets were bonded to the enamel surface and the shear bond strength (SBS) and adhesive remnant index were tested. The release of calcium (Ca), phosphorus (P), strontium (Sr), and fluoride (F) ions from adhesive specimens in distilled water was evaluated after 15, 30, 60 days. The remineralization effect was observed the microhardness and surface morphology using scanning electron microscopy with energy dispersive spectroscopy. Results Except for the FAp, no significant differences in SBS were observed (p > 0.05). Ion release results showed Ca, P, Sr, and F ions were detected in the Sr-FAp group up to 60 days. The Sr-FAp group showed the highest microhardness (p < 0.05), and the largest amount of fluorapatite-like layer (Ca/P: 1.69) was formed after 60 days of immersion. Conclusion The Sr-FAp group showed acceptable SBS while exhibiting the highest microhardness and the most pronounced formation of a fluorapatite-like layer, indicating its effectiveness in preventing WSLs during orthodontic treatment.

Effect of Topical Fluoride Application Temperature on Recharge and Rerelease in Different Restorative Materials

2026-02-01T00:00:00Z

Title: Effect of Topical Fluoride Application Temperature on Recharge and Rerelease in Different Restorative Materials Authors: Kim, Ji-Eun; Hong, Ji-Yeon; Kim, Kwang-Mahn; Kwon, Jae-Sung Abstract: Introduction and aims: This study aimed to evaluate the influence of topical fluoride application temperature on the recharge and rerelease behaviour of three fluoride-containing restorative materials treated with 1.23% acidulated phosphate fluoride (APF) gel and 8% stannous fluoride (SnF2). Methods: Specimens of an alkasite-restorative material (Cention N), a resin-modified glass ionomer (Fuji II LC), and a conventional glass ionomer (Fuji IX GP) were prepared (n = 32 per material; n = 8 for each combination of fluoride agent and temperature). After an initial 64-day fluoride release phase in deionized water, samples were recharged with APF gel or SnF2 at room temperature (23 +/- 2 degrees C) or high temperature (HT) (55 +/- 2 degrees C) for 4 minutes. Subsequent fluoride rerelease was measured for 32 days. Physicochemical properties of fluoride agents, including viscosity, temperature, and pH, were analysed. Elemental mapping of fluoride and tin distribution was performed using scanning electron microscope-energy-dispersive X-ray spectroscopy. Results: All restorative materials initially showed rapid fluoride release that decreased over 64 days. After topical application, cumulative fluoride rerelease was significantly higher under HT than room temperature across all groups (P < .05), particularly with APF gel. RMGI demonstrated the greatest fluoride rerelease, while CGI showed the highest initial release. Scanning electron microscope-energy-dispersive X-ray spectroscopy revealed higher fluoride content at HT across all materials in both surface and cross-sectional analyses, regardless of the fluoride agent used. Tin distribution was detected only in SnF2-treated groups. Conclusion: Elevated application temperature significantly improves the fluoride recharge and sustained release capacity of restorative materials, with outcomes depending on the fluoride agent and material type.(c) 2025 The Authors. Published by Elsevier Inc. on behalf of FDI World Dental Federation. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)