Ricardo Faria Almeida

Retrievable Metal Ceramic Implant-Supported Fixed Prostheses with Milled Titanium Frameworks and All-Ceramic Crowns: Retrospective Clinical Study with up to 10 Years of Follow-Up

PURPOSEnThe purpose of this study was to report on the outcome of metal ceramic implant-supported fixed prostheses with milled titanium frameworks and all-ceramic crowns.nnnMATERIALS AND METHODSnThe clinical study included 108 patients (67 women, 41 men), mean age of 58.6 years (range: 34-82), followed between 9 months and 10 years (post occlusal loading). The mean follow-up time for all patients in the study was 5 years. A total of 125 prostheses were fabricated. The data were divided into 2 groups. Development group (DG): 52 patients with 66 prostheses (28 maxillary, 38 mandibular) fabricated with individual Procera crowns (Alumina copings, Nobel Biocare AB) and Allceram ceramics (Ducera Dental GmbH) cemented onto a CAD/CAM fabricated Ti framework (Nobel Biocare AB) with pink ceramic (Duceram, Ducera Dental GmbH) that replicated the missing gingival tissues. Routine group (RG): 56 patients with 59 prostheses (49 maxillary, 10 mandibular) fabricated with individual Procera crowns (Zirconia copings and Nobel Rondo Zirconia Ceramic; Nobel Biocare AB) cemented onto a CAD/CAM fabricated Ti framework (Nobel Biocare AB) with pink acrylic resin (PallaXpress Ultra, Heraeus Kulzer GmbH) that replicated the missing gingival tissues. Primary outcome measures were prosthetic survival and mechanical complications. Secondary outcome measures were biological complications testing the retrievability characteristic of the prosthesis. Survival estimates were calculated on the patient level with the Kaplan-Meier product limit estimator (95% confidence intervals [CI]). Data were analyzed with descriptive and inferential analyses.nnnRESULTSnThe cumulative survival rates for the implant-supported fixed prostheses were 92.4% for the DG at 10 years and 100% for the RG at 5 years (overall 96%) (Kaplan-Meier). Mechanical complications occurred in 44 patients (DG: 29 patients, 36 prostheses; RG: 15 patients, 16 prostheses); the large majority were crown fractures, occurring in 48 patients (DG: 33 patients, 36 prostheses; RG: 15 patients, 16 prostheses). In the DG, univariate analysis of logistic regression disclosed the presence of a metal ceramic implant-supported fixed prosthesis opposing dentition as a risk factor for crown fracture (OR = 1.97). Biological complications occurred in 33 patients (DG: 18 patients; RG: 15 patients), the majority being peri-implant pathologies in 19 patients (DG: 9 patients, RG: 10 patients). All situations were resolved except one in the DG that led to fixture and prosthesis loss.nnnCONCLUSIONSnThe results of this study indicated that, within the limitations of this study, the CAD/CAM protocol is acceptable for definitive prosthetic rehabilitation. This protocol provided these patients with a good prognosis on a middle- to long-term basis (5 years).

An Innovative Framework Supporting SME Networks for Complex Product Manufacturing

Current market dynamics require European SME’s to focus on complex products manufacturing and to build non-hierarchical business networks, to assure competitiveness and sustainability. Such trend demands appropriate methods for network formation and management, including reference collaboration processes and supporting ICT tools. This paper presents a framework to support SME’s in the creation and management of non-hierarchical networks designed and developed within the European RTD project Net-Challenge. This framework includes methodologies, processes and ICT decision support tools aiming at the efficient creation and management of these networks assuring quick response times and competitive and differentiated offerings.

Dynamic and collaborative business networks in the fashion industry

In order to stay competitive and avoid being smashed by large companies, small- and medium-sized enterprises (SMEs) need to establish and manage dynamic and non-hierarchical networks to respond to market opportunities, ensuring a quick response, unique products with competitive prices and high product quality. This article proposes an innovative methodological approach and ICT platform to support non-hierarchical collaboration between SMEs for customised product design and manufacturing. The ICT services are based on mapping a methodology on an open source platform in order to apply low cost solutions to SMEs. Two case studies in the fashion industry have been analysed and used to test the proposed approach for network management.

Reference model for collaborative manufacturing of customised products: applications in the fashion industry

In the recent years, it has been confirmed both by theory and by practice that organisational models need to include networking strategies to cope with the current competitive environment. Different collaboration levels can characterise supply chains, virtual organisations (VO) and business communities; however, managing different networking scenarios is extremely important to allow SMEs to respond to market opportunities, ensuring a quick response, unique products with competitive prices and high product quality. This paper proposes an innovative methodological approach to support collaboration amongst SMEs for customised product design and manufacturing based on the VO concept. The work is based on mapping the methodology with the most important processes characterising the life of a VO and defining the operative practices to be performed within this type of network. This paper presents two case studies in the fashion industry, where the proposed approach for network management was tested and analysed.

Methodology for non-hierarchical collaboration networks for complex products manufacturing

To successfully compete in the market, European SMEs will have to adopt new business models and establish dynamic and non-hierarchical networks, assuring quick response, fast time to market, differentiated offerings and competitive prices. Sustainability will be found in high-variety and low-volume businesses, related with complex products design and manufacturing. This paper presents a Methodology concept, developed by the European project Net-Challenge, supporting SMEs in building and operating non-hierarchical business networks for complex products manufacturing with Engineer-To-Order (ETO) or Assemble-To-Order (ATO) strategies.

Deciding KAT and Hoare Logic with Derivatives

Kleene algebra with tests (KAT) is an equational system for program verification, which is the combination of Boolean algebra (BA) and Kleene algebra (KA), the algebra of regular expressions. In particular, KAT subsumes the propositional fragment of Hoare logic (PHL) which is a formal system for the specification and verification of programs, and that is currently the base of most tools for checking program correctness. Both the equational theory of KAT and the encoding of PHL in KAT are known to be decidable. In this paper we present a new decision procedure for the equivalence of two KAT expressions based on the notion of partial derivatives. We also introduce the notion of derivative modulo particular sets of equations. With this we extend the previous procedure for deciding PHL. Some experimental results are also presented.

The Influence of Crown-to-Implant Ratio on Short Implant Marginal Bone Loss

PURPOSEnThere is a need for more studies evaluating the marginal bone loss (MBL) of rehabilitations in the posterior regions of extremely resorbed maxillae and mandibles supported by short-length dental implants with a high crown/implant ratio (C/I-R). The aim of this study was to evaluate the influence of the C/I-R in implants on MBL considering dental implants with 4 mm of width and 7 mm of length.nnnMATERIALS AND METHODSnThis retrospective cohort study included 59 patients (mean age of 52.8 years) rehabilitated with at least one implant 4 mm in width and 7 mm in length, with an anodically oxidized surface and external connection on the premolar or molar positions, supporting a fixed prosthesis, and in function for a period of 36 months. Periapical radiographs at 36 months were used to calculate the C/I-R and MBL. The Spearman correlation coefficient was used to test the correlation between C/I-R and MBL. The level of significance was set at 5%.nnnRESULTSnOne hundred eighteen implants from 59 patients were evaluated. The mean ± SD MBL was 0.67 ± 0.63 mm. The C/I-R mean ± SD was 2.53 ± 0.79 mm. Thirty implants presented a C/I-R ≤ 2, while 88 implants had a C/I-R > 2. A weak nonsignificant inverse correlation (r = -0.081; P = .383, Spearman) was registered between C/I-R and MBL.nnnCONCLUSIONnWithin the limitations of this study, it is possible to conclude that implant-supported fixed prostheses with C/I-R > 2 do not correlate positively with MBL.

Surgical Non-Regenerative Treatments for Peri-Implantitis: a Systematic Review

ABSTRACT Objectives The purposes of the present study were 1) to systematically review the literature on the surgical non-regenerative treatments of peri-implantitis and 2) to determine a predictable therapeutic option for the clinical management of peri-implantitis lesions. Material and Methods The study search was performed on primary database MEDLINE and EMBASE from 2005 until 2016. Sequential screenings at the title, abstract, and full-text levels were performed. Clinical human studies in the English language that had reported changes in probing depth (PD) and/or bleeding on probing (BOP) and/or radiologic marginal bone level changes after peri-implantitis surgical non-regenerative treatment at 6-month follow-up or longer were included accordingly PRISMA guidelines. Results The first electronic and hand search resulted in 765 citations. From 16 full-text articles reviewed, 6 were included in this systematic review. Surgical non-regenerative methods were found to be efficient in reducing clinical parameters. BOP and PD values were significantly decreased following implantoplasty and systematic administration of antibacterials, but not after local application of chemical compounds or diode laser. Similarly, significant improvement in clinical and radiographic parameters was found only after implantoplasty compared with resective surgery alone. We found significant heterogeneity in study designs and treatments provided among the pooled studies. All of the studies revealed an unclear or high risk of bias. Conclusions Surgical non-regenerative treatment of peri-implantitis was found to be effective to reduce the soft tissue inflammation and decrease probing depth. More randomized controlled clinical trials are needed to assess the efficacy of surgical non-regenerative therapy of peri-implantitis.

Individual lithium disilicate crowns in a full-arch, implant-supported rehabilitation: a clinical report.

This clinical report presents the clinical outcome of a maxillary full-arch implant-supported fixed rehabilitation with lithium disilicate reinforced glass ceramic monolithic crowns opposing a mandibular metal-acrylic implant-supported fixed rehabilitation in a 62-year-old woman. Eight implants were successfully placed (four maxillary, four mandibular), and no complications occurred in the postoperative or maintenance periods. Six months after delivery, the maxillary and mandibular prostheses were found to be clinically, biologically, and mechanically stable, and the patient was satisfied with the esthetics and her ability to function. Although the present indications for the use of lithium disilicate are still restricted to tooth-borne restorations, it is possible to successfully rehabilitate edentulous patients through implant-supported fixed prostheses using lithium disilicate reinforced glass ceramic monolithic crowns.

Partial Rehabilitation with Distally Tilted and Straight Implants in the Posterior Maxilla with Immediate Loading Protocol: A Retrospective Cohort Study with 5-Year Follow-up.

PURPOSEnThe purpose of this study was to compare the outcome of fixed partial prostheses in the posterior maxilla with two axially placed implants or one implant placed distally tilted and one axially placed implant following an immediate loading protocol.nnnMATERIALS AND METHODSnA sample of 60 patients was divided into two groups-group 1: 30 patients rehabilitated with one axially placed implant and one implant placed distally tilted in the posterior maxilla; group 2: 30 patients rehabilitated with two axially placed implants in the posterior maxilla. Outcome measures were implant survival based on function, marginal bone resorption, and the incidence of mechanical and biologic complications at 5 years; inferential statistics were used to analyze the intergroup and intragroup differences. The level of significance was set at 5%.nnnRESULTSnNo significant differences were found between both groups in survival, complications, or marginal bone resorption. One axially placed implant was lost at 58 months in group 1, rendering a cumulative survival estimate at 5 years of 96.7% and 98.3% in group 1 and the total sample, respectively (P = .317). Mechanical complications occurred in 16 patients (26.7%; n = 8 patients in each group; [P > .999]), consisting of fractures in the provisional prosthesis (n = 8 patients), chipped ceramics of the definitive prosthesis (n = 2 patients), loosening of prosthetic components (n = 5 patients), and fracture of an attachment screw (n = 1 patient). Biologic complications occurred in 5 patients (8.3%; group 1 = 4 patients; group 2 = 1 patient; [P = .161]), consisting of peri-implant pathology. The mean ± SD marginal bone loss was 2.02 ± 0.36 mm and 1.90 ± 0.69 mm for groups 1 and 2, respectively (P = .235). In group 1, the mean ± SD marginal bone loss was 1.92 ± 0.48 mm and 2.11 ± 0.44 mm for the implant placed distally tilted and axially placed implant, respectively; the difference was significant (P < .001).nnnCONCLUSIONnWithin the limitations of this study, the use of implants placed distally tilted together with axially placed implants or two axially placed implants in the fixed partial rehabilitation of the posterior maxilla are viable treatment alternatives.