Purpose: To evaluate the marginal adaptation and fracture resistance of three computer-aided design/computer-assisted manufacturing hybrid dental materials with different occlusal thicknesses.Methods: Ninety single-molar crowns were digitally fabricated using a milled hybrid nanoceramic (Cerasmart, CE), polymer-infiltrated ceramic network (PICN, Vita Enamic, VE), and 3D-printed materials (Varseosmile, VS) with occlusal thicknesses of 0.8, 1, and 1.5 mm (10 specimens/group). Anatomical 3D-printed resin dies (Rigid 10K) were used as supporting materials. A CEREC MCX milling unit and a DLP-based 3D printer, Freeform Pro 2, were utilized to produce the crown samples. Before cementation, the marginal adaptation, absolute marginal discrepancy (AMD), and marginal gap (MG) were assessed using micro-CT scanning. After cementation with self-adhesive resin cement, fracture resistance was evaluated using a universal testing machine. The number of fractured crowns and the maximum fracture values (N) were recorded. Data were statistically analyzed using both one- and two-way ANOVA, followed by Tukey’s honestly significant difference (HSD) test.Results: For all occlusal thicknesses, the VS crowns demonstrated the lowest AMD and MG distances, significantly different from those of the other two milling groups (P < 0.05), whereas CE and VE did not differ significantly (P > 0.05). All VS crowns were fractured using the lowest loading forces (1480.3±226.1 to 1747.2±108.7 N). No CE and 1 and 1.5 mm VE crowns fractured under a 2000 N maximum load.Conclusions: All hybrid-material crowns demonstrated favorable marginal adaptation within a clinically acceptable range, with 3D printing yielding superior results to milling. All materials could withstand normal occlusal force even with a 0.8 mm occlusal thickness.

The aim of this study was to specifically explore the effects of morpholine on chemical surface treatments of aged resin composites contaminated with saliva to new resin composite repair strength. One hundred and thirty five resin composite specimens were fabricated and thermocycled to replicate an aged resin composite. These aged resin composites were randomly separated into nine groups (n = 15) depending on the various surface contaminants and surface treatment techniques. These groups were as follows: group 1—no surface treatment; group 2—no saliva + adhesive agent; group 3—no saliva + morpholine + adhesive agent; group 4—no saliva + morpholine; group 5—saliva; group 6—saliva + adhesive agent; group 7—saliva + morpholine + adhesive agent; group 8—saliva + morpholine; and group 9—saliva + phosphoric acid + adhesive agent. A mold was covered on the top of the specimen center and then filled with resin composite. The shear bond strengths and failure modes were examined. The collected data was analyzed using one-way ANOVA, and the significance level was determined using Tukey’s test. Group 5 (3.31 ± 0.95 MPa) and group 6 (4.05 ± 0.93 MPa) showed the lowest bond strength statistically, while group 3 (23.66 ± 1.35 MPa) and group 7 (22.88 ± 1.96 MPa) showed the most significantly high bond strength. The bond strength in group 2 (16.41 ± 1.22 MPa) was significantly different from that in group 1 (9.83 ± 1.13 MPa), group 4 (10.71 ± 0.81 MPa), and group 8 (10.36 ± 1.53 MPa), while group 9’s (17.31 ± 1.48 MPa) SBS was not significantly different. In conclusion, the application of morpholine on aged resin composite with or without contamination with saliva prior to the application of the adhesive agent increased the bond strength of aged resin composite repaired with new resin composite (p < 0.05).

This study assessed the susceptibility to staining and surface roughness of white-spot lesions (WSLs) treated with resin infiltration (RIT) and microabrasion (MA) under simulated aging through thermocycling in red wine. Seventy-eight extracted human premolars with artificial WSLs were divided into three groups: untreated WSLs (control), RIT-treated (ICON^®, DMG), and MA-treated (Opalustre^®, Ultradent). Each group was further split: one subgroup immersed in artificial saliva and the other thermocycled in red wine. The color change (∆E) and surface roughness (R_a) were measured before and after staining using a spectrophotometer and a non-contact profilometer. Thermocycling in red wine increased color change (ΔE) across all groups, with the highest values observed for MA (43.94 ± 3.57), followed by RIT (31.40 ± 4.89). Surface roughness (R_a) was highest in untreated WSLs (0.61 ± 0.18 µm) and lowest in RIT (0.15 ± 0.03 µm). While RIT and MA similarly improved WSL appearance, RIT exhibited superior smoothness. These findings suggest that RIT provides a more durable surface with reduced roughness, although staining susceptibility remains comparable to MA. Moderate positive correlation was found between ΔE and Ra, indicating that roughness is one of the factors influencing color changes.

This in vitro study investigated the fracture resistance of three ceramic-reinforced polymer (CRP) crowns—Cerasmart^® 270 (CE; milled), VarseoSmile Crown Plus^® (VS; 3D-printed) and the newly developed Hassawat-01 (HS; 3D-printed)—luted with cements of different elastic moduli. The principal hypothesis was that neither the CRP type nor the modulus of cement would significantly affect fracture resistance. Ninety-nine mandibular first molar resin dies were restored with 1 mm thick CE, VS, or HS crowns (n = 33 each) and luted with Maxcem Elite^®, RelyX Unicem^®, or Ketac Cem^® (n = 11 per subgroup). Occlusal cement morphology was evaluated using Micro-CT. Fracture resistance was measured using a universal testing machine. Crowns luted with Maxcem or RelyX withstood forces >2000 N without visible failure. Ketac-luted crowns showed reduced fracture resistance. CE-Ketac fractured in 4 of 11 specimens. VS-Ketac exhibited cracks or complete fractures (1795.2 ± 156.7 N), whereas HS-Ketac showed only superficial cracking (1732.6 ± 127.3 N). CRP crowns luted with lower-modulus resin cements demonstrated superior fracture resistance compared with those luted with glass-ionomer. VS exhibited both cracking and occasional complete fractures, whereas HS exhibited only surface cracking. All materials withstood loads greater than typical masticatory forces, supporting HS as a promising alternative within the CRP.

Janaphan K, et al. J Periodontal Implant Sci. 2026 Jan;56:e2. https://doi.org/10.5051/jpis.2502400120

Background: Altered passive eruption (APE) is one of the etiological factors associated with excessive gingival display and is commonly treated with esthetic crown lengthening (ECL). However, existing classification systems provide limited guidance for selecting appropriate treatment approaches. Objectives: The aim of this study was to evaluate (1) the expected outcome of ECL in eliminating unattractive excessive gingival display (4 mm) based on digital smile assessment and (2) the distribution of teeth and patients according to the modified APE classification. Methods: Forty-two Thai patients with APE underwent clinical examination, digital smile assessment, intraoral scanning, and CBCT. Predicted gingival display (PGD) was calculated to assess the expected outcomes of ECL. The modified APE classification, incorporating CEJ–BC distance and buccal bone thickness, was analyzed at both the tooth and patient levels. Results: A total of 252 maxillary anterior teeth were assessed. Most patients (78.57%) presented with APE and hyperactive upper lip. The mean gingival display (GD) was 6.04 ± 1.76 mm, with GD ≥ 4 mm observed in 92.86% of patients. The mean PGD was 3.56 ± 1.71 mm, and ECL was predicted to reduce GD to < 4 mm in 66.67% of patients. Teeth were classified as Class I (28.97%), II (15.48%), III (41.27%), and IV (14.28%); only Types II (11.9%) and III (88.1%) occurred at the patient level. Conclusions: ECL performed at the CEJ level is predicted to eliminate excessive gingival display in approximately two-thirds of APE patients. The modified APE classification offers guidance for selecting surgical approaches, highlighting the necessity of open-flap procedures and the limited applicability of flapless approaches.