Is Ammonium Hydrogen Difluoride a Solution for Zirconia Surface Conditioning?

INTRODUCTION: This research investigated the topographical features and phase transformation of high-translucent monolithic zirconia after different surface conditioning methods. METHODS: Zirconia slabs were divided into six groups according to surface treatment method. Group I: etched with hydrofluoric acid (HF); Group II: etched with an experimental acid solution (EAS); Group III: melt-etched with ammonium hydrogen difluoride (AHD); Group IV: air abrasion (AB); Group V: etched with EAS after air abrasion (AB+EAS); Group VI: melt-etched with AHD after air abrasion (AB+AHD). Surface topographies of specimens were documented by scanning electron microscopy (SEM). Tetragonal-to-monoclinic phase transformation was detected by X-ray diffraction and surface evaluation of zirconia specimens; surface roughness and contact angle measurements were performed. The data were statistically analyzed by the Kruskal- Wallis test and post hoc tests (P⟨0.05). RESULTS: The acid-etched zirconia groups (Group I, II, and III) showed the lowest contact angle and surface roughness values (P⟨0.05), while the air abrasion groups (Group IV, V, VI) showed the highest. The SEM images also supported these results. CONCLUSION: Within the limitations of this in vitro study, treating the monolithic zirconia surfaces with EAS or AHD after air abrasion may be recommended to alter the zirconia surfaces.

Immediate implant placement in fresh sockets versus implant placement in healed bone for full-arch fixed prostheses with conventional loading.

This retrospective study assessed the success of immediate and non-immediate implants installed in patients undergoing planned extraction of all remaining teeth and rehabilitation with implant-supported full fixed prostheses. Patients in need of dental implants for full fixed prostheses to replace teeth extracted in the maxilla and mandible were included in this study. Dental implants were installed in the same surgical procedure, immediately at the extraction site, or in healed bone. Implant success, complications, and failures were recorded during follow-up. Forty-one patients with 512 implants were included in the study. Healing progressed uneventfully for 501 installed implants, but nine implants were lost in the non-immediate group and two were lost in the immediate group, during a mean follow-up of 44.9 months. All failures in both groups were observed in the maxilla. The success rate was the same in both groups, at 97.8%. This retrospective analysis showed that with thorough patient evaluation, the extraction of all residual teeth and implant installation in a single surgical procedure is a safe and predictable treatment modality for the successful rehabilitation of the edentulous patient with a fixed prosthesis.

Fracture strengths of chair-side-generated veneers cemented with glass fibers.

INTRODUCTION: CAD/CAM (computer-aided design and computer-aided manufacturing) systems have refreshed the idea of chair-side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of CAD/CAM-generated ceramic veneers. Therefore, this study compared the fracture strengths of ceramic veneers produced at chair side and cemented with or without glass fibers with those of composite veneers. METHODOLOGY: Thirty intact mandibular incisors were randomly divided into three groups ( n = 10) and treated with CAD/CAM-fabricated veneers cemented with dual-cure composite resin luting cement (CRLC; Group 1), CAD/CAM-fabricated veneers cemented with a glass fiber network (GFN) and dual-cure CRLC (Group 2), and a direct particulate filler composite veneer constructed utilizing fiber and a restorative composite resin (Group 3). The specimens were tested with a universal testing machine after thermal cycling treatment. RESULT: The loads at the start of fracture were the lowest for traditionally fabricated composite veneers and higher for CAD/CAM-generated. Veneers cemented either without or with the GFN. The failure initiation loads (N) for the veneers were 798.92 for Group 1, 836.27 for Group 2, and 585.93 for Group 3. The predominant failure mode is adhesive failure between the laminates and teeth for Group 1, cohesive failure in the luting layer for Group 2, and cohesive laminate failure for Group 3, which showed chipping and small fractures. CONCLUSION: Ceramic material is a reliable alternative for veneer construction at chair side. Fibers at the cementation interface may improve the clinical longevity and provide higher fracture strength values.