This study aims to compare the shear bond strength (SBS) and Weibull characteristics between a luting composite resin and both printable and two different machinable ceramic–glass polymer materials. A total of 36 substrates were prepared, with 12 in each group. Printable substrates (12 mm × 12 mm × 2 mm) were printed by using permanent crown resin (3D-PR). Machinable substrates were obtained from Cerasmart 270 (CS) and Vita Enamic (VE) blocks (2 mm in thickness). The bonding surfaces of substrates were polished and airborne abraded (50 µm Al₂O₃). A self-adhesive luting composite resin (RelyX U200, 3M ESPE, St. Paul, MN, USA, SLC) was applied on substrates with the help of a cylindrical (Ø3 × 3 mm) mold. The SBS test was conducted using a universal test machine. The SBSs of three materials were compared using a one-way analysis of variance (ANOVA) (α = 0.05). The Weibull modulus was calculated for each material. The Kruskal–Wallis and chi-square tests were carried out for the failure mode analysis. There was no significant difference between the SBSs of the three materials (p = 0.129). The Weibull modulus was 3.76 for the 3D-PR, 4.22 for the CS, and 6.52 for the VE group. Statistical analysis showed no significant difference between the failure modes of the groups (p = 0.986). Mixed-failure fractures were predominantly observed in all three groups. The results show that the SBS of the SLC to printable 3D-PR is comparable to that of CS and VE material. Failure modes of printable 3D-PR show similar results with two different machinable ceramic–glass polymers.

Öz Amaç: Bu çalışmanın amacı; Londra Atlas tekniğinin ve Cameriere’nin 3. molar olgunluk indeksinin (I3M) Türk popülasyonunda 18 yaş yasal sınırının belirlenmesinde radyolojik diş yaşının doğruluğunu, özgüllüğünü ve duyarlılığını değerlendirmektir. Gereç ve Yöntemler: Çalışma kesitsel gözlemsel olarak tasarlanmıştır. Çalışmaya 14 - 21 yaş aralığında toplamda 804 (470 kadın, 334 erkek) birey dahil edilmiştir. 18 yaş yasal sınırının belirlenmesinde Londra Atlas ve I3M yöntemleri kullanılarak farklı iki araştırmacı tarafından radyolojik diş yaşının doğruluğu, özgüllüğü ve duyarlılığı değerlendirilmiştir. Bulgular: 18 yaş eşiğini belirlemede, Londra Atlas tekniği % 88.74 duyarlılık, % 87.37 özgüllük ve % 88.1 doğruluk gösterirken, I3M tekniği % 95.54 duyarlılık, % 75.50 özgüllük ve % 85.5 doğruluk göstermiştir. İki teknik arasındaki uyumluluk düzeyine bakıldığında ise (κ = 0.813) elde edilen uyumluluğun iyi düzeyde olduğu bulunmuştur. Sonuç: I3M ve Londra Atlas teknikleri Türk toplumunda 18 yaş eşiğini belirlemede benzer performanslar göstermiştir. Yaş tahminini güçlendirmek için Londra Atlas ve I3M tekniklerinin kombine kullanımı sonuçları değiştirmemiştir. Londra Atlas tekniğinin Türk toplumuna uyumunu görebilmek için daha çok çalışmaya ihtiyaç vardır. Anahtar kelimeler: adli tıp, panoramik radyografi, pedodonti, yaş tayini

Background: Three-dimensional (3D) printed occlusal splints are increasingly used in dental practice, but their repairability remains a concern. This study aimed to evaluate the effect of cleaning tablets on the shear bond strength of 3D-printed occlusal devices repaired with either polymethyl methacrylate (PMMA) or 3D printer resin. Methods: A total of 60 specimens (10×10×2 mm) were manufactured using 3D-printer occlusal device resin with a digital light processing 3D printer. Surfaces were polished with abrasive papers with grits #1000 and #1200 for 1 minute for each grit, and then PMMA and 3D printer resin were applied using a standardized apparatus with the cylindrical cavity 3 mm in diameter in the center, without any surface pretreatment. All specimens were kept in artificial saliva at 37°C for 7 days in an incubator. Then, half of the specimens for each repair material (n = 15) were immersed in a cleaning tablet solution for 90 minutes to simulate 1 month of clinical use (PMMA-T and 3D-T groups). Meanwhile, the other specimens were preserved in distilled water (PMMA-DW and 3D-DW groups). The shear bond test was conducted using universal testing equipment with a crosshead speed of 5 mm/min. The data were statistically analyzed using 2-way analysis of variance (α = .05). Results: The highest bond strength value was observed in the 3D-DW group (6.03 ± 2.28 MPa), whereas the lowest was observed in the PMMA-T group (3.70 ± 1.95 MPa). No statistically significant differences were found between the groups. No significant interaction was found between the cleaning tablet exposure and repair material type (F = 0.164, P = .688). Conclusion: Although the differences were not statistically significant, 3D printer resin repair material showed higher bond strength, probably due to similar chemical composition, and cleaning tablets reduced the bond strength of both repair materials.

The main challenges to the widespread clinical application of three‐dimensional (3D)‐printed customized trays include cost and time limitations. This study examined how changing the internal structure of 3D‐printed materials used for customized trays affects flexural strength (FS), flexural modulus (FM), manufacturing time, and material weight. Specimens (64 × 10 × 3.3 mm) were printed using a light‐sensitive liquid resin. The internal structures of control specimens were completely filled, whereas the internal structures of test groups comprised vertical bars spaced 1 mm (Test 1) or 2 mm (Test 2) apart. Specimens were weighed and then subjected to a three‐point bending test to evaluate their FS and FM. Data were analyzed using one‐way ANOVA and Tukey's test, with Weibull analysis applied to FS values. Control specimens had the highest FS (106 ± 4 MPa), while Test 2 specimens demonstrated the highest FM (6101 ± 1407 MPa). No significant differences were found between Test 1 and Test 2 specimens in FS or FM. Test 2 specimens had the lowest mean weight (1440 ± 42 mg). Manufacturing times were 80 min for control and Test 1 specimens and 60 min for Test 2 specimens. Including spaces in the internal structure of 3D‐printed custom tray material saves material and manufacturing time while maintaining mechanical properties.