Studies on 6-sector-site deployment in downlink LTE

Mobile data traffic is expected to increase massively in the following years. Consequently, service operators are induced to increase the capacity of their networks continually to attract more subscribers and maximize their revenues. At the same time, they want to minimize operational costs and capital expenditures. Among the alternatives that aim to increase the network capacity, higher order sectorization, and in particular a six sectorized configuration, is nowadays attracting a lot of attention for LTE macro-cell deployments since a higher number of sectors per site results in improved site capacity and coverage. A six sectorized configuration is attractive for both roll-out phase and growth phase of the network. In the roll-out phase, the radio access network is planned with 6-sector sites instead of 3-sector sites with the advantage that less sites are needed for the same capacity and coverage requirements. In the growth phase, the six sectorized configuration can be used to upgrade existing 3-sector sites where the traffic grows beyond the current sites' capabilities. Therefore, no additional expensive and time consuming contracts need to be signed for the locations of the new sites, while the existing sites are used more efficiently. However, although potentially a 6-sector site can offer a double capacity than a 3-sector site, several factors prevent the capacity from growing proportionately to the number of sectors. Consequently, there is an uncertainty on whether the capacity gain is high enough to justify the extra costs of the additional equipment and, more specifically, whether the 6-sector-site deployment is more economically attractive than a 3-sector-site deployment. The aim of this report is to solve this uncertainty. First, we present the main factors that affect the capacity gain. Next, we quantify the impact of these factors on the capacity gain in downlink LTE with the use of a system level simulator. Finally, we use the results of the simulation study as inputs for an economic study to access the reasons for a possible deployment of 6-sector sites instead of 3-sector sites for LTE

Six-mm versus 10-mm long implants in the rehabilitation of posterior edentulous jaws : a 5-year follow-up of a randomised controlled trial

To compare the clinical outcome of 6-mm and 10-mm long implants in partially edentulous posterior areas. MATERIALS AND METHODS: Twenty-four patients, with a partially edentulous area in the jaws with a height and width allowing the positioning of 2 to 3 adjacent 10 7 4.1 mm implants without any augmentation procedure, were randomly allocated according to a parallel group design to receive 6-mm long or 10-mm long implants. A total of 54 implants were placed (26 7 6 mm and 28 7 10 mm implants). Patients were restored 8 weeks after surgery and were followed for 5 years. Outcome measures were prosthesis and implant survival, as well as marginal bone level changes and complications. RESULTS: After 5 years, 18 patients were available. One 6 mm implant failed during the healing period and its related prosthesis could not be placed. No implants were lost after loading. The 6 mm group registered 5 complications (1 mucositis, 3 prosthesis decementations and 1 chipping), while only 3 were registered in the 10 mm group (2 decementations and 1 chipping). The difference in complications between the two groups was not statistically significant (P = 0.39). Marginal bone loss at 5 years was 0.43 and 0.24 mm with the 6 mm and 10 mm groups, respectively (not statistically significant; difference between the two groups 0.19 mm; SD 0.23 mm; 95% CI -0.34;0.73; t test P = 0.42) CONCLUSIONS: Implant and prosthetic survival and success rates were similar between prostheses supported by 6-mm or 10-mm long implants. Conflict-of-interests statement: The present study was supported by grant 369_2004 from ITI, Basel, Switzerland used to provide free implants and prosthetic components to the patient. Authors declare no conflict of interest

Stratification of prosthetic complications by manufacturer in implant-supported restorations with a 5 years’ follow-up: systematic review of the literature

INTRODUCTION: Prosthetic complications on implant-supported restorations have been documented in several papers published in the literature. Several manufacturers are present on the market but results are often cumulated and may thus be misleading. The objective of the present review is to assess the prosthetic complications of implant-supported restorations with particular interest of the results obtained with prostheses from different manufacturers. EVIDENCE ACQUISITION: A manual search of Medline/PubMed was carried out up to June 2016, yielding a total of 6832 articles, which were narrowed down to 1450, then 347 abstracts to include 55 papers after full text reading. Papers with at least 5 years of follow-up reporting on prosthetic complications of single and fixed partial prosthesis were included. Prosthetic complications were divided into mechanical and technical complications, and reported in a table. EVIDENCE SYNTHESIS: Overall 14.4% of prosthetic complication was found for a total of 6623 restorations followed for an average of 7.4 years (range 5-16 years). Results where then sorted and compared. Single crowns were affected by 1.4% of mechanical complications and 10.9% of technical complications after a mean of 7.4 years. Fixed partial prosthesis were affected by 2.5% of mechanical complications and 18% of technical complications. Screw-retained and cemented restorations were calculated to have a 5 years rate of complications of 21.2% and 9.3%, respectively, which demonstrated a statistically difference with fisher exact test with P<0.1. Only 3 manufacturers presented more than 10 articles and were directly compared with Fisher's exact test with P<0.1. The incidence of overall complications was estimated to be after 5 years of 11.2%, 10.8% and 13.8% for Straumann, Nobel, and Astratech, respectively, but dividing results in mechanical and technical complications, gave different results. Straumann was estimated to have less mechanical complications after 5 years in respect to Nobel and Astratech, but the three were similar for technical complications. CONCLUSIONS: although studies present very different material and methods and do not report all data, some conclusions can be made. The difference between mechanical complications lead the authors to suppose that there might be a difference in results obtained by different implant abutment connections. It is also noticed that all papers were published by expert clinicians and universities research centers that apply rigid surgical and prosthetic protocols and use original abutments

The use of short dental implants in clinical practice : literature review

When anatomic structures and ridge resorption limit the placement of a standard implant, the clinician can apply augmentation techniques or use short implants. A literature review was carried out to evaluate the differences in survival rate and the rational use of short implants. Electronic search (MEDLINE) and manual search have been performed to select papers from 2000 to 2008. Of all the inclusion criteria the most relevant were: 1) studies with data on short implants; 2) studies on humans; 3) prospective, longitudinal, retrospective and multicenter studies; 4) no restrictions were applied about study design; 5) no implant type selection was applied. Exclusion criteria were: 1) studies concerning treatment of patients with conditions possibly affecting survival or success rates of implant treatment; 2) studies concerning treatment of patients with non-treated periodontal disease; 3) implants placed in non-healed ridge, such as postextractive short implants. A total of 13 studies fulfilled the inclusion criteria. Most of the studies have reported different survival rate for short and standard implants. The difference is not significant. The recent literature have demonstrated a similar survival rate for short and standard implants. Older articles have demonstrated a lower survival rate for short implants. The treatment planning is a key factor for success in the use of short implants. Some of the parameters the clinician should consider are: 1) area to rehabilitate as well as bone quality; 2) length of the implant; 3) implant diameter; 4) type of implant and surface treatment; 5) crown to implant ratio of the final prostheses; 6) type of prostheses; 7) connection to other implants; 8) occlusal/ parafunctional load; 9) prosthetic complications. Although in the literature there are no studies that analyze short implant survival from the point of view of each key factors, it can be assumed that a careful treatment planning can lead the clinician to obtain a successful rehabilitation

Reproducibility of Buccal Gingival Profile Using a Custom Pick-Up Impression Technique : A 2-Year Prospective Multicenter Study

Purpose The aim of this study was to transfer the provisional restoration emergence profile to the final implant-supported restoration and to buccal gingival margin (BGM) stability after 2 years of function. Materials and Methods A total of 33 patients were recruited for treatment of single gaps by means of 33 implant-supported restorations. Fixed provisional crowns were screwed to the fixture and adjusted until the complete peri-implant soft tissue maturation was achieved. After 12 weeks, a second fixture impression was taken by means of a pick-up customization technique in order to transfer the clinical aspect of the peri-implant soft tissues to the master cast. A definitive restoration was delivered. A standardized method from digital photographs was used to assess the gingival margin modification (BGM) from the provisional (P) to the definitive prosthesis installation at baseline (D0), and after 1 (D1) and 2 years (D2) of function. Also, marginal bone loss (MBL) was calculated after 1 (D1) and 2 years (D2) of definitive restoration function. Results The BGM index at the time of the final restoration installation (D0) was 0.12 \ub1 0.33 mm if compared with the BGM position of the provisional restoration (P); it was of 0.12 \ub1 0.46 mm after 1-year of follow-up (D1) and of 0.31 \ub1 0.21 after 2 years of function (D2). No significant difference was calculated between measurements in different follow-up visits (p > 0.05). No significant MBL was measured between the baseline (D0) and the 1-year follow-up (p = 0.816) with a mean MBL value of 0.2 \ub1 0.1 mm. Similar result was calculated after 2 years (p = 0.684) with a mean MBL value of 0.3 \ub1 0.2. Conclusion A modified impression pick-up may be helpful to reproduce the gingival margin position from the provisional to the definitive restoration. Moreover, the gingival zenith position during the follow-up period seemed to be stable. Clinical Significance The modification of the standard impression pick-up technique may contribute to reproducing a natural emergence profile of esthetic implant prosthetic restorations (from the provisional to the definitive restoration.) With this technique, implant soft tissues stability around CAD-CAM (computer aided design - computer aided manufacturing) abutments can be easily obtained, and the customized abutment shape may better support the scalloped peri-implant soft tissues architecture, especially in anterior areas