Journal of dentistry最新文献

Objectives: Although pre-treatment parameters for subtractive computer-aided design/computer-aided manufacturing (CAD/CAM) materials have been thoroughly investigated, data regarding additive restorative materials designed for permanent use in the oral cavity are scarce. This study investigated the effects of abrasive materials and blasting pressure on the bond strength of 3D-printed resins used in permanent restorations.

Methods: A total of n = 44 test specimens additively manufactured from Formlabs' 'Permanent Crown Resin' were prepared. Three groups with n = 11 specimens were airborne-particle abraded with 50 µm aluminium oxide at 1 bar, 2 bar or 3 bar. The control group did not receive any further airborne-particle abrasion after post-processing with 50 µm glass beads. Cylindrical superstructures were bonded to the prepared surfaces using RelyX Unicem 2. The bonded specimens were then subjected to artificial ageing via thermocycling. Subsequently, shear bond strength (sbs) tests were conducted. Data were analysed with the Kruskal-Wallis test (α = 0.05).

Results: After post-processing with glass beads, average shear bond strength values of 10.13 ± 7.62 MPa were achieved. When using aluminium oxide and 1 bar blasting pressure, significantly higher average sbs values of 25.57 ± 7.04 MPa were revealed (p = 0.009). The bond strength increased with higher blasting pressures (28.14 ± 6.35 MPa at 2 bar (p = 0.005); 30.15 ± 6.46 MPa at 3 bar (p < 0.001)). However, the shear tests revealed increased failure within the specimen base at higher blasting pressures.

Conclusion: Bond strength significantly improved when airborne-particle abrasion with aluminium oxide was applied. However, increased airborne-particle abrasion pressure led to more failures at the base plate level of the specimens.

Clinical significance: Aluminium oxide increases the adhesive strength of 3D-printed dental restorative materials. Although the adhesive bond increased slightly with increasing airborne-particle abrasion pressure, the 3D restorative materials also exhibited an increased failure rate within the restorative material in the shear bond strength test with increasing blasting pressure.

Objectives: This in vitro study aimed to evaluate the impact of different alignment algorithms and CAD software programs on alignment accuracy (trueness and precision) and processing time.

Methods: A mandibular typodont was digitized using a laboratory scanner (L2i) to obtain a reference STL (STLr) file. It was then scanned with an intraoral scanner (Primescan) and digitally duplicated ten times (n=10). Each scan was aligned with the STLr using 42 combinations of 3D CAD software and alignment algorithms. The tested software programs included Blender for Dental, BlueSkyPlan, Dental CAD App (Exocad), Medit Design, NemoSmile, and Meshmixer. Alignment accuracy (trueness and precision) and processing time were recorded using Python software (v3.8). Statistical analysis was performed with a two-way ANOVA test (α = .01) to identify overall differences, followed by a post hoc Tukey Honestly Significant Difference test (α = .05) to establish rankings.

Results: Significant differences in alignment accuracy were observed based on the software and algorithm used, affecting both trueness (p<.01) and precision (p<.01). Processing time also varied significantly (p<.01). Post hoc analysis identified the optimal algorithm for each software, revealing variations in trueness, precision, and processing time among the optimal versions. Medit Design achieved the best overall performance by combining high accuracy with the fastest processing time, while Meshmixer exhibited the lowest accuracy due to its lack of advanced algorithms.

Conclusions: The choice of CAD software and alignment algorithm significantly influences alignment accuracy and efficiency. Best-fit and section-based provided the best results, offering valuable insights into the optimization of digital workflows in prosthodontics.

Clinical significance: Alignment protocols must be tailored to the specific CAD software program used, as no universal protocol was effective across all tested software. Optimizing alignment protocols reduces errors, enhances prosthodontic outcomes, and improves the reliability and efficiency of clinical and laboratory workflows, ultimately ensuring better patient care and treatment success.

Objectives: To assess the differences between the traditional thermoformed clear aligners (TFA) and the emerging 3D-printed clear aligners (DPA) by comparing their mechanical and chemical properties, manufacturing process, accuracy trueness and precision, and effect on sustainability. To evaluate whether 3D-printing is more efficient than thermoforming in the manufacturing of clear aligners; Data: Data was collected from scientific articles related to 3D-printed aligners' properties and comparative cross-referenced articles related to the thermoformed aligners' properties; Sources: The sources assessed to retrieve the articles were scientific databases Scopus and PubMed; Study selection: A PICO format research question guided the study selection by both assisting in the formulation of keyword combinations and establishing a set of inclusion and exclusion criteria to meet this review's objectives; Results: The results indicate that both aligners have good mechanical properties, but the DPA distinguished themselves with two novel properties, shape memory and design flexibility. Additionally, they exerted a consistent force profile in contrast to the TFA. The DPA have higher accuracy, trueness and precision than the TFA, however similar to the thermoforming process, direct-printing also varied the thickness of the DPA from the original master STL model. There are limited studies on sustainability and biocompatibility of the DPA; Conclusions: Following this review, it can be concluded that 3D-printed aligners are likely to serve as an alternative to the thermoformed aligners in the near future, seeing their innovative and promising properties. However, further experimental studies with higher quality of evidence and an emphasis on randomization are necessary to confirm current laboratory-based studies' findings and address important limitations before promoting the aligners to a larger audience.

Clinical significance: Seeing the design flexibility benefits of 3D-printing technology, and the shape memory property of currently marketed 3D-printed aligners, this could positively impact the accomplishment of precise, desired orthodontic outcomes, also while potentially reducing clinical treatment time.

Aim: This study aimed to evaluate salivary cytokine levels and the prevalence of cariogenic bacterial species in children with active dental caries compared to caries-free peers.

Methods: This cross-sectional study involved forty randomly selected children aged 7-9 years, who were divided into caries-active or caries-free groups. DNA was extracted from supragingival plaque using the DNeasy kit and analysed. Microbial profiling was conducted using HOMINGS 16S rRNA gene sequencing. Saliva samples were also collected and analysed using multiplex cytokine bead assays on the Luminex system to assess cytokine levels.

Results: The caries-active group exhibited significantly higher relative abundance of genera Leptotrichia, Veillonella, and Kingella (p<0.05). At the species level, Streptococcus sanguinis, Leptotrichia shahii, Streptococcus mutans, Leptotrichia sp. HOT_498, TM7[G-1] sp. HOT_346, Rothia dentocariosa were significantly enriched in the caries-active group. In females, IL-15 and IL-1β were significantly elevated in the caries-active group, with no cytokine differences observed in males or overall levels. The relative abundance of Leptotrichia shahii, Streptococcus mutans, Streptococcus sanguinis, TM7[G-1] sp. HOT_346, Abiotrophia defectiva, and Rothia dentocariosa significantly correlated with cytokines, including Aggrecan, BAFF, CD-40L, IL-1β, IL-5, IL-8, IL-11, IL-15, IL-17, IL-23, IL-28A, MIP-3α, Pentraxin 3, and TNF-α. In the caries-free group, only Leptotrichia hongkongensis showed a significant association with IL-10.

Conclusion: Distinct microbiome differences at both the genus and species levels were observed between caries-active and caries-free groups. Salivary cytokine levels were similar between the groups, except for higher IL-15 and IL-1β in females from the caries-active group. Correlations between bacteria and cytokines in the caries-active group highlight the need for further research on the microbiome-immune interaction in caries development.

Clinical significance: Microbiome profiles, cytokine levels, and their potential correlation in caries-active children suggest that further study and understanding of these factors could help identify individuals at higher risk for caries and guide preventive care.

Objectives: This review aimed to evaluate the outcomes of ridge augmentation techniques and bio-materials for alveolar bone regeneration, addressing inconsistencies across studies. A decision tree is provided to guide clinicians in selecting optimal approaches for diverse clinical scenarios.

Data and sources: An extensive search was conducted across electronic databases, including PubMed, Scopus, and Embase, alongside dental implant and prosthodontics journal portals. Reference lists of relevant articles were also manually reviewed up to October 2024.

Study selection: Inclusion criteria were established to emphasize English-language human clinical trials investigating regenerative techniques and materials utilized for ridge augmentation prior to implant placement.

Conclusions: Selecting defect-specific regenerative approaches is crucial for successful outcomes in alveolar bone augmentation. While autografts remain the gold standard, advancements in allografts, xenografts, synthetics, and biological enhancers are transforming the field. Distraction osteogenesis is also gaining prominence as a promising technique. Clinicians should leverage these innovations to tailor treatments to individual patient needs for optimal results. The decision tree developed categorizes alveolar bone anomalies and suggests tailored approaches based on anticipated resorption patterns.

Clinical significance: Careful patient evaluation and tailored technique selection, combined with advancements in biomaterials and tissue engineering, are essential for achieving optimal outcomes in ridge augmentation, particularly for challenging vertical defects.