Extraction of Maxillary Impacted Teeth with Simultaneous Immediate Full Mouth Loading Using Long Implant: A Case Report.

Here, we describe the provision of an implant-supported prosthesis in a patient with impacted teeth in the maxilla, which complicated implant placement and necessitated utilization of the extraction sockets of previously impacted teeth and residual submerged roots. The patient was a 63-year-old man who visited our clinic with the chief complaint of difficulty in mastication. Numerous residual roots were observed in the maxilla, and radiographic imaging revealed that the residual roots of teeth #13 and #16 were fully impacted. The patient complained of a strong sensation of a foreign body in the area of a denture support overlying these residual roots. Therefore, the impacted teeth were extracted, 5 implants placed, and a temporary prosthesis provided. Given the necessity of placing the implant through the extraction socket of the impacted canine (#13), favorable initial stability was achieved using a long (>20 mm) implant. Moreover, autogenous bone obtained by osteotomy was grafted onto the extracted impacted tooth socket. The clinical condition was stable at approximately 1 year after implant placement and so the final prosthesis was delivered, with periodic check-ups being performed every 3 months thereafter. After 4 years, the patient has reported no symptoms. Clinically, there are no signs of inflammation, and the postoperative condition is deemed to be very favorable.

A 3-year follow-up of ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) frameworks for fixed dental prostheses.

PURPOSE: Zirconia/alumina nanocomposite stabilized with cerium oxide (Ce-TZP/A) shows significantly higher mechanical strength than yttrium-oxide-partially-stabilized zirconia (Y-TZP) and allows post-sintered machining that does not require any subsequent treatment. The aim of this prospective study was to assess the clinical performance of veneered Ce-TZP/A frameworks for fixed dental prostheses. METHODS: Fifteen patients with 22 Ce-TZP/A fixed prostheses were included in this study. The fixed dental prostheses were cemented with resin cement (baseline) and were evaluated at baseline and at 1, 6, 12, 24 and 36 months after cementation. Clinical events, including fracture and loss of retention, secondary caries, and marginal integrity, were recorded. The biologic outcome was judged by comparing the pre-treatment and post-treatment bleeding on probing (BOP), and probing pocket depth (PPD) of the abutment teeth. Radiographic examination was also performed at 12, 24 and 36 months. RESULTS: The mean observation period was 35.9±5.5 months. During this period, one abutment tooth was extracted due to root fracture and the survival rate was 95.2%. No significant change in BOP, PPD, and radiographic image was found during the 36-month follow-up period. CONCLUSION: Within the limitations of this study, Ce-TZP/A was found to provide sufficient stability as a framework material in all regions. Special attention, however, must be paid to designing framework that provides sufficient support for the veneer. Furthermore, studies with longer observation periods and more patients are needed.

Influence of the rigidity of a provisional restoration supported on four immediately loaded implants in the edentulous maxilla on biomechanical bone-implant interactions under simulated bruxism conditions: a three-dimensional finite element analysis.

PURPOSE: The aims of this study were to (1) establish a biomechanical model that simulates the full-arch restoration supported by immediately loaded implants, which is customized for individual patients, and (2) clarify the effect of the implant placement and rigidity of a provisional restoration on the biomechanical response at the bone-implant interface. MATERIALS AND METHODS: Three-dimensional finite element analysis models of a maxillary full-arch prosthesis supported by four immediately loaded implants were created from computed tomography data of maxillary edentulous patients. Displacements of the implants and equivalent stress on the bone around the implants under the loading conditions that simulated sleep bruxism were then calculated for these models. The effects of the implant placement angle (vertical or inclined), the reinforcement of the provisional restoration (with or without reinforcement), and the implant length on the maximum displacements of each implant were investigated, in addition to the average equivalent stress of the bone around the implant. RESULTS: A longer implant and rigid restoration with reinforcement have the potential to reduce implant displacements and associated bone stress; however, the rigidity of the restoration had a much more significant effect on these parameters. CONCLUSIONS: The rigidity of full-arch provisional restorations supported by four immediately loaded implants should be improved by reinforcements, which could ensure the successful achievement of osseointegration by reducing load-induced micromovements of the implants.

Implant-supported fixed dental prostheses with CAD/CAM-fabricated porcelain crown and zirconia-based framework.

Recently, fixed dental prostheses (FDPs) with a hybrid structure of CAD/CAM porcelain crowns adhered to a CAD/CAM zirconia framework (PAZ) have been developed. The aim of this report was to describe the clinical application of a newly developed implant-supported FDP fabrication system, which uses PAZ, and to evaluate the outcome after a maximum application period of 36 months. Implants were placed in three patients with edentulous areas in either the maxilla or mandible. After the implant fixtures had successfully integrated with bone, gold-platinum alloy or zirconia custom abutments were first fabricated. Zirconia framework wax-up was performed on the custom abutments, and the CAD/CAM zirconia framework was prepared using the CAD/CAM system. Next, wax-up was performed on working models for porcelain crown fabrication, and CAD/CAM porcelain crowns were fabricated. The CAD/CAM zirconia frameworks and CAD/CAM porcelain crowns were bonded using adhesive resin cement, and the PAZ was cemented. Cementation of the implant superstructure improved the esthetics and masticatory efficiency in all patients. No undesirable outcomes, such as superstructure chipping, stomatognathic dysfunction, or periimplant bone resorption, were observed in any of the patients. PAZ may be a potential solution for ceramic-related clinical problems such as chipping and fracture and associated complicated repair procedures in implant-supported FDPs.

[Study on color stability of composite resins for a facing crown polymerized with high output photo-curing unit].

PURPOSE: This study investigated the color stability of composite resins for a facing crown cured with a high output photo-curing unit (Hyper LII, YAMAHACHI DENTAL MFG., CO.). METHODS: Four brands of composite resins for a facing crown after polymerization with Hyper LII were immersed in coffee. Color measurement was carried out before and 1, 2, and 4 weeks after immersion, and the results were compared. RESULTS: 1. After immersion in coffee, the L* values decreased gradually, the a* values showed little change, and the b* values increased gradually in all resins. 2. The difference in the color difference values (deltaE*ab) between each material became greater with time; the deltaE*ab after 4 weeks immersion were from 3.0 [Dentacolor (DEC), dentin specimen] to 6.3 [Solidex (SOL), enamel specimen] on polished surfaces, and from 0.9 [Gradia (GRA), dentin specimen] to 5.2 (SOL, enamel specimen) on non-polished surfaces. However, the deltaE*ab were 1/3 to 1/5 better than those of our previous studies. 3. The enamel specimens showed larger color differences than the dentin specimens. 4. When polished surfaces were compared with non-polished surfaces, Cesead II (CEII), DEC and SOL showed almost equal color differences while GRA showed larger color differences. CONCLUSIONS: This study suggests that composite resins for a facing crown cured with a high output photo-curing unit result in a decrease of color changes with time and an improvement of color stability.