Collagen Fibres Orientation in the Bone Matrix around Dental Implants: Does the Implant's Thread Design Play a Role?

The aim of this study was to analyse the influence of different thread shapes of titanium dental implant on the bone collagen fibre orientation (BCFO) around loaded implants. Twenty titanium dental implants, divided for thread shapes in six groups (A-F) were analysed in the present study. All implants were immediately loaded and left in function for 6 months before retrieval. The parameters evaluated under scanning electron microscope were the thread width, thread depth, top radius of curvature, flank angle, and the inter-thread straight section. Two undecalcified histological sections were prepared from each implant. Birefringence analysis using circularly polarized light microscopy was used to quantitively measure BCFO. For groups A-F, respectively, transverse BCFO was 32.7%, 24.1%, 22.3%, 18.2%, 32.4%, and 21.2%, longitudinal BCFO was 28.2%, 14.5%, 44.9%, 33.1%, 37.7%, and 40.2%. The percentage differences between transverse and longitudinal orientation were 4.50% (A), 9.60% (B), -22.60% (C), -14.90% (D), -5.30% (E), and -19.00% (F). Following loading, the amount of transverse and longitudinal BCFO were significantly influenced by the thread shape. The greater flank angles and narrower inter-thread sections of the "V" shaped and "concave" shaped implant threads of groups A and B, respectively, promoted the predominance of transverse BCFO, compared to groups C-F (p < 0.05). A narrow inter-thread straight section promotes transverse BCFO, as do "V" shaped and "concave" shaped threads, which can thus be considered desirable design for implant threads.

Solid index impression protocol: a hybrid workflow for high accuracy and passive fit of full-arch implant-supported restorations.

AIM: The purpose of this article is to present the preliminary clinical results obtained with a novel hybrid digital-analog technique, the solid index impression protocol (SIIP), which uses a solid index to capture accurate impressions of multiple implants for the fabrication of implant-supported fixed full arches (FFAs). MATERIALS AND METHODS: This pilot study was based on five patients, each treated with a FFA supported by four implants. Three months after implant placement, impressions were taken for all patients with an intraoral scanner (IOS) (direct digital impression) and with the SIIP, using a custom tray consisting of four hollow cylinders connected with a bar. This index was linked to the implant transfers and transferred to the laboratory, and the definitive FFAs were fabricated based on it. The outcomes of the study were the passive fit of implant superstructures and the accuracy of the models generated by the SIIP, inspected using a coordinate measuring machine (CMM) and reverse engineering software, and compared with the accuracy of direct digital impressions. RESULTS: Excellent clinical precision and passive fit were obtained in all five implant-supported FFAs fabricated with the SIIP. One year after delivery, all FFAs were functional without any complication. Differences in accuracy were found between the SIIP and direct intraoral scanning. CONCLUSIONS: The SIIP seems to represent a viable option for capturing accurate impressions for the fabrication of clinically precise implant-supported FFAs with a hybrid digital-analog workflow. Further studies are needed to confirm these results.

The ability of marginal detection using different intraoral scanning systems: A pilot randomized controlled trial.

PURPOSE: To assess the clinical ability of marginal detection of different intraoral optical scanning (IOS) systems. METHODS: The Ethics Committee of the University of Siena, Italy approved the research project. Thirty patients in need of an onlay/inlay with supra-gingival margins were included and randomly divided in three groups of 10 (3× n=10) according to the IOS for chairside capturing:(A) GC-Europe (Aadva); (B) True-Definition-TD; (C) Trios. A total of 1 scans from each IOS test group (A-C), were obtained clinically and stored as STL-files. In addition, corresponding conventional impressions were taken for all 30 patients, poured with stone, and then processed by a laboratory scanner (Aadva), serving as controls. All 60 STL-files were imported to the Exocad platform for analysis. The horizontal distance between each preparation margin and the adjacent tooth was measured using the ruler tool in the software. The distance at which the detection of the margin started to become visibly unclear was recorded for the horizontal distances. Data was processed statistically by one-way ANOVA (P> 0.05). RESULTS: No statistically significant inter-test group differences could be identified (IOS A-C). The minimum distance from which a clear margin was visible, was 4.5 (SD 0.1) mm for all images, regardless of which IOS was used. Under these experimental clinical conditions, all tested IOS performed similarly. In contrast, all margins of the controls were clearly visible. CLINICAL SIGNIFICANCE: None of the tested intraoral scanning systems in this study were capable of recording a clear impression when the cervical margin for a posterior partial crown was located at a distance of less than 0.5 mm from the interproximal neighbor.

Implantology and otorhinolaryngology team-up to solve a complicated case.

PURPOSE: The aim of this article was to highlight the importance of the collaboration between implantologists and ear, nose, and throat (ENT) specialists to treat complex cases. MATERIALS AND METHODS: A 46-year-old patient underwent a maxillary sinus elevation and implant placement 3 years before but because of a severe postop infection, the patient was treated with functional endoscopic sinus surgery (FESS) and lost the graft and the implants. Later, the patient consulted us and was referred to an ENT specialist because of sinus opacity. She underwent a second functional endoscopic sinus surgery (FESS); various ENT consultations and computer tomographies (CTs) were performed to assess sinus health. RESULTS: After having confirmed with sinus health, sinus elevation, implant placement, and loading were performed with success. CONCLUSION: Collaboration between the implantologist and ENT specialist is necessary to distinguish between nonpathological membrane thickening because of the healing process after FESS and a pathological thickening due to infection.

Protocol for rearing and using mosquitoes for flight path tracking and behavioral characterization in wind tunnel bioassays.

Mosquito behavioral assays are an important component in vector research and control tool development. Here, we present a protocol for rearing Anopheles mosquitoes, performing host-seeking behavioral bioassays, and collecting 3D flight tracks in a large wind tunnel. We describe steps for setting up host-seeking landing assays, both as a non-choice and as a dual-choice assay, and analyzing flight tracks. This protocol can be applied in the research of several behavioral traits, including nectar seeking, resting, mating, and oviposition behavior. For complete details on the use and execution of this protocol, please refer to Carnaghi et al.1.

Visual and thermal stimuli modulate mosquito-host contact with implications for improving malaria vector control tools.

Malaria prevention relies on mosquito control interventions that use insecticides and exploit mosquito behavior. The rise of insecticide resistance and changing transmission dynamics urgently demand vector control innovation. To identify behavioral traits that could be incorporated into such tools, we investigated the flight and landing response of Anopheles coluzzii to human-like host cues. We show that landing rate is directly proportional to the surface area of thermal stimulus, whereas close-range orientation is modulated by both thermal and visual inputs. We modeled anopheline eye optics to theorize the distance at which visual targets can be detected under a range of conditions, and experimentally established mosquito preference for landing on larger targets, although landing density is greater on small targets. Target orientation does not affect landing rate; however, vertical targets can be resolved at greater distance than horizontal targets of the same size. Mosquito traps for vector control could be significantly enhanced by incorporating these features.

Tilted trans-sinus implants for the treatment of maxillary atrophy: case series of 35 consecutive patients.

PURPOSE: To evaluate tilted trans-sinus implants for rehabilitation of the atrophic maxilla. MATERIALS AND METHODS: A case series of 35 patients (32 consecutive edentulous and 3 partially edentulous patients) treated with trans-sinus dental implants is presented. Edentulous patients received 4 or 6 implants depending on anatomic conditions and a 12-unit final restoration; partially edentulous patients received 2 implants supporting a 3-unit partial fixed bridge. RESULTS: Thirty-five patients (14 men, 21 women) underwent rehabilitation. Thirty-two patients with 190 implants placed received a full-arch fixed prosthesis supported by axial and trans-sinus tilted implants. Three patients each received 2 implants with a 3-unit fixed restoration. The mean age at surgery was 59.2 ± 9.5 years. The cumulative survival rate was calculated only for the full-arch fixed prosthesis group and was 98.42%. Crestal bone loss averaged 0.9 ± 0.4 and 0.8 ± 0.5 mm for the axial and tilted implants, respectively, at the 12-month evaluation. Biological complications at the implant level were 1 case of peri-implantitis and 3 cases of mucositis; no patient developed sinus infections. The prosthetic complications encountered were screw loosening in 17.5% of cases and chipping of the esthetic part in 30% of cases. These complications were easily resolved chairside and did not lead to prosthetic failure. CONCLUSIONS: Trans-sinus tilted implants and sinus membrane distal displacement appear to be a viable minimally invasive alternative for the treatment of maxillary atrophy.

Sinus floor elevation with crestal approach and immediately loaded post-extraction implants.

Alveolar ridges in the posterior maxilla are often compromised by reduced bone volume. This anatomic condition often limits dental implant placement, mostly because of limited vertical bone availability without prior or simultaneous sinus augmentation. When at least 5 mm of residual bone are present, osteotome techniques are used as a less invasive alternative to the lateral window approach to increase bone volume in the posterior posterior region of the maxillary jaw. Implants are generally placed simultaneously for four to six months after performing osteotome-mediated sinus floor elevation, depending upon the residual crestal bone remaining beneath the sinus floor. However, unlike common indications, in order to shorten the treatment period, this report aims to show a challenging case where, through a thorough surgical protocol, two compromised maxillary teeth were replaced by two immediately loaded post-extraction implants contextually to an osteotome-mediated sinus floor elevation.

Customized-3D zirconia barriers for guided bone regeneration (GBR): clinical and histological findings from a proof-of-concept case series.

OBJECTIVES: The aim of this case series was to evaluate, clinically and histologically, customized-3D zirconia barriers manufactured for guided bone regeneration (GBR) procedures. METHODS: Seven healthy consecutive patients with severe bone atrophy (two of them with a bilateral atrophy) were selected for a GBR procedure with a zirconia barrier. In a 3D software (DentalCad, Exocad GmbH, Germany), a virtual bone graft was designed and a shell was designed covering the graft; a standard tessellation language (.STL) file was obtained and milled (M1, Zirkonzahn, Italy) using a 1200 MPa zirconia (Prettau, Zirkonzahn, Italy). Nine GBR surgeries (8 upper-posterior jaw, 1 lower-posterior jaw) were performed using autogenous bone chips mixed with xenograft (SmartBone, IBI-SA, Switzerland / BioOss, Geistlich, Switzerland) covered with a zirconia barrier, fixed by means of screws. After healing, implant sites were prepared with a trephine bur, collecting a bone biopsy, and dental implants were inserted (Neodent, Straumann Group, Switzerland). Specimens were histologically analyzed. RESULTS: Eight successful surgeries were recorded; one zirconia barrier got exposed after one month of healing but no signs of infection were present till the barrier was removed. In all cases it was possible to insert implants with no additional bone augmentation procedures. Histological evaluations showed the presence of intense deposition of new bone. CONCLUSIONS: Within the limitations of the present case series, the tested customized-3D zirconia barriers confirmed good clinical and histological performances, and, even in case of premature exposure, did not show signs of infection. Preliminary results suggest they are effective for GBR procedures. Further research is necessary with a larger sample size. CLINICAL SIGNIFICANCE: The presented barriers could be a viable alternative to titanium-reinforced polytetrafluoroethylene membranes and customized meshes.

Healing of Post-Extraction Sockets Filled with Anorganic Bovine Bone and Covered with a Xenogeneic Collagen Matrix. Radiological 2D and 3D Results of a Pilot Study to Assess Dimensional Stability.

Analysis of short-term results regarding dimensional stability of post-extraction sockets managed via a preservation protocol using deproteinized bovine bone matrix and a xenogeneic collagen matrix. Materials and methods Fifteen patients needing extraction of one single-rooted premolar tooth were treated in a pilot study. Five patients were treated in each centre. After tooth extraction, sockets were filled with anorganic bovine bone matrix and covered with a xenogeneic collagen matrix. Six months later, implants were placed. Dimensional changes in the treated sites were digitally evaluated using the best-fit superimposition of pre-and post-socket preservation models. Results After six months of healing, the vertical reduction of the grafted sites was 0.31 ± 0.24 mm (p < 0.001). Volumetric analysis of superimposed models showed an average palatal-lingual contraction of 0.33 ± 0.51 mm3 (p = 0.02). At the vestibular level, the average contraction was found to be 0.8 ± 0.3 mm3 (p < 0.001). Finally, the analysis of linear variations in the treated sites on a single sagittal section at the crystal level, and at 3 and 7 mm apically respect to the crest, both towards the vestibule and palate, generally showed more marked resorption at the crestal level compared to apical measurements. Conclusion: The clinical protocol herein employed for socket preservation showed a positive effect in preventing the physiological post-extraction remodeling.