International Journal of Computerized Dentistry, 02/2014

If a 3D radiograph, which in today's dentistry often consists of a CBCT dataset, is available for computerized implant planning, the 3D planning should also consider functional prosthetic aspects. In a conventional workflow, the CBCT is done with a specially produced radiopaque prosthetic setup that makes the desired prosthetic situation visible during virtual implant planning. If an exclusively digital workflow is chosen, intraoral digital impressions are taken. On these digital models, the desired prosthetic suprastructures are designed. The entire datasets are virtually superimposed by a "registration" process on the corresponding structures (teeth) in the CBCTs. Thus, both the osseous and prosthetic structures are visible in one single 3D application and make it possible to consider surgical and prosthetic aspects. After having determined the implant positions on the computer screen, a drilling template is designed digitally. According to this design (CAD), a template is printed or milled in CAM process. This template is the first physically extant product in the entire workflow. The article discusses the options and limitations of this workflow. Keywords: digital, virtual, intraoral impression, CBCT, prosthetic planning, registration, implant planning

Purpose: To describe a chairside method for producing implant guides based solely on digital data and present a first assessment of in vitro accuracy on plaster models. Material and Methods: Twenty-four implants were planned and pilot drillings were performed according to a new protocol, which is based on the registration of CBCT and CAD/CAM data. Chairside-milled one-piece drill guides were used to transfer the virtual plan into reality. Accuracy measurements were acquired. Results: Chairside-milled drill guides were successfully fabricated and accuracy for pilot drillings was between 0.17 and 1.3 mm. Conclusion: Within the limits of this experimental study, chairside-milled drill guides are feasible and do not require any preparation before CBCT scanning. Keywords: accuracy, dental implantology, cone-beam computed tomography (CBCT), dental CAD/CAM, computer-aided surgery (CAS), drill template, surgical guides

This study analyzed the influence of platform switching on the stress/strain distribution of vertically loaded implants. Employing finite element analysis, the aim of this study was to determine the distribution of stresses and strains generated by a simulated vertical load on different implant models positioned in the molar region with respect to changes of implant design and biomechanics. Two different implant designs, one with and one without platform switching, with the same length (11.5 mm) and diameter of (3.80 mm) were analyzed. Both virtual implant-bone models were subjected to a load of 500 N. The results showed that the maximum stress/strain in implant-bone samples was located in the area of the implant neck, with stress/strain values decreasing in the apical direction. It was found that the implant design with platform switching developed lower stresses and strains than the implant design without platform switching. Keywords: platform switching implant, finite element analysis, biomechanics

The aim of the study was to determine the retentive strength of monolithic all-ceramic crowns cemented on titanium implant abutments. 225 crowns (75 crowns each of Mark II, Empress CAD, and e.max CAD) were milled using a CAD/ CAM system. The crowns were cemented onto sandblasted titanium implant abutments using five luting agents (Multilink Implant, Variolink II, RelyX Unicem, Fujicem, and Panavia 2.0). After thermocycling, the crowns were removed using a universal testing machine. The location of luting agent residue on the abutment and inner crown surfaces was evaluated. Statistical analysis was performed uisng ANOVA with the Bonferroni correction. In comparing the luting agents, no significant difference was found between Vita Mark II and Empress CAD. For e.max CAD, the luting agent RelyX Unicem had a significantly higher mean retentive strength than did Multilink Implant (p = 0.003) or Panavia 2.0 (p = 0.001). In comparing the ceramic materials, e.max CAD showed significantly higher pull-off strengths than the other two ceramic materials when the luting agents RelyX Unicem and Fujicem were used (all p 0.001). The residues of nearly all luting agents were located entirely or almost entirely (75%-100%) on the inner crown surfaces of all ceramic materials, except for the luting agent GC Fujicem, which left more luting agent residue (0%-75%) on the abutment surfaces of all ceramic materials. In comparing the five luting agents, significant differences in the resulting retentive strength were only found for the ceramic material e.max CAD. The other ceramic materials did not show significant differences in retentive strength, independent of the luting agent. Keywords: implant, ceramic, retentive strength, CAD/CAM, luting agent, cement

The greatest key to successful implant therapy is proper placement of the implant in the jaw bone. The key to proper placement is careful preoperative planning. When planning implant treatment, it is important to take the relevant anatomical features and their later prosthetic consequences into account. This is done using a radiographic template of the planned restoration, which until now had to be made by a dental technician. The radiographic template must be inserted in the patient's mouth during radiographic imaging so that the dentist can visualize the prosthetic plan. Implant planning is thus performed according to the backward planning principle. In the novel, fully digital approach to dental implant planning presented here, the prosthetic proposal is designed using computer-aided design software and integrated into a three-dimensional radiograph. This article explains how the technology works and reviews the available data. In addition, the clinical workflows for the SiCAT Optiguide and Sirona Cerec Guide virtual implant planning methods will be described and compared with conventional implant planning methods. Finally, the indications and contraindications for the two methods will be discussed. Keywords: implantology, virtual implant planning, backward planning, Optiguide, Cerec Guide, CBCT, Cerec, CAD/CAM, registration, surgical guide

With the Cerec 4.2 software version, implant abutments and crowns can be fabricated using an impressionless technique. The intraoral optical impression is taken using ScanPosts. The custom-made abutments are connected with an adhesive titanium base and can therefore be secured with high torques without tensile stress. Keywords: abutment, titanium bases, ScanPost, zirconia, lithium disilicate, implant, impressionless