Purpose: To assess the clinical performance of a two-piece zirconia implant system, with a focus on biologic complications. Materials and Methods: A total of 39 patients received 91 two-piece zirconia implants. The patients were recruited from two private clinics and were monitored for 5 to 12 years (median: 5.6 years). The primary outcomes were biologic complications, such as peri-implant infections (peri-implant mucositis and peri-implantitis), and the secondary outcome was radiographically evident marginal bone loss (MBL). Results: Three patients (7.7%) with 9 total implants (9.9%) presented with peri-implant mucositis. MBL that did not exceed the first thread was evident at 32 mesial sites (35%) and 25 distal sites (27.4%). MBL exceeding the first thread but not the third thread was evident at 6 mesial and 5 distal sites (thread pitch: 0.7 mm). Only one peri-implant pocket deepened (4 mm) and showed bleeding; however, the estimated MBL did not exceed 1.65 mm. No peri-implantitis occurred, and no implant was lost. Conclusions: This prospective study shows high survival rates and a seemingly low prevalence of biologic and prosthetic complications for this two-piece zirconia implant system over an observation period of up to 12 years. Keywords: bone resorption, dental implantation, osseointegration, peri-implantitis, two-piece zirconia implants

Titanium oral implants are still considered "state of the art" in implant dentistry, with well-documented survival rates. However, their grayish color and high prevalence of peri-implant infections have resulted in controversial discussion as to whether tooth-like-colored, metal-free zirconia ceramic implants provide sufficient potential to be considered equal regarding treatment outcomes. The present position paper has been composed upon invitation by the European Association of Osseointegration in order to provide an update on the current level of evidence regarding zirconia implants in clinical trials. To date, most available and scientifically documented zirconia implant systems are one-piece implants that require an experienced surgeon and prosthodontist due to the restricted flexibility in cases of compromised angulation or vertical positioning. Taking this limitation into account, there is evidence of a comparable outcome for one-piece zirconia implants compared to titanium implants for the fixed replacement of one to three missing teeth. In contrast, currently available clinical data evaluating two-piece zirconia implants with an adhesively bonded implant-abutment interface suggest an inferior outcome. Data evaluating the clinical applicability of screw-retained solutions, even if revealing sufficient fracture resistance in laboratory investigations, are still missing. High survival rates were reported for all-ceramic reconstructions supported by zirconia implants, but with increased technical complications; ie, fractures of the ceramic veneer in the case of bilayered restorations. Sufficient clinical evidence for recommending monolithic approaches is limited to single crowns.

Aims: While numerous materials are available for sinus floor elevation, plant-based alternatives still hold promise of overcoming concerns about allogeneic or xenogeneic materials. Thus, the present authors designed a randomised clinical trial to histologically compare an almost pure hydroxyapatite (HA) to a biphasic calcium phosphate comprising 80% β-tricalcium phosphate (β-TCP) and 20% hydroxyapatite (β-TCP/HA), all of phycogenic origin. Materials and methods: Twenty patients scheduled for lateral window sinus floor elevation were randomised to either an HA or a β-TCP/HA group. Biopsy specimens were taken 3 months after sinus floor elevation and during implant surgery after 6 months. One ground section per biopsy specimen (N = 40) was stained, scanned and histomorphometrically analysed for new bone, old bone, soft tissue, graft, bone infiltration of graft, bone-to-graft contact and penetration depth. Results: At 6 months, more new bone was seen in the β-TCP/HA group (P = 0.011), whereas more residual graft was present and in more extensive contact with new bone in the HA group. More pronounced alterations, and smaller particle sizes, of graft surrounded and infiltrated by bone were seen in the β-TCP/HA group. The less extensive bone-to-graft contact in the β-TCP/ HA group reflected a more advanced state of resorption, while infiltration of residual graft material by bone was also increased in this group. Conclusions: Proper healing was seen in both groups, with the graft materials guiding the formation of new bone, which grew especially well through the particles of the highly osteoconductive and resorptive β-TCP/HA material. HA was very stable, without significant resorption, but was extensively in contact with new bone after 6 months. Keywords: biocompatible materials, bone substitutes, calcium phosphates, hydroxyapatites, sinus floor elevation This study was partially supportedby Dentsply Sirona Implants(I-BI-14-077; Mannheim, Germany) and the materials investigated in the study were providedfree of charge for patients’ use;

Aim: The production of individual tooth replicas has two applications in dental practice: tooth autotransplantations and dental root analogue implants. These applications require a particularly high degree of precision. The purpose of this study was to establish and evaluate a method for fabricating individual 3D-printed tooth replicas. Materials and methods: 10 patients requiring extraction of a wisdom tooth and a preoperative cone beam computed tomography (CBCT) scan were included; exclusion criteria were intraoperative fragmentation or fracture of the tooth. 3D Slicer 4.6.2 was used for tooth segmentation and model generation based on CBCT data. The tooth replicas were manufactured by selective laser melting (SLM). The extracted teeth and 3D-printed replicas were scanned and tested for surface deviations in CloudCompare 2.8.1. Results: The mean absolute surface deviation between the 3D-printed teeth and the corresponding extracted teeth ranged from 0.13 to 0.25 mm, with standard deviations of 0.10 to 0.21 mm; 95% of the measured surface points deviated less than 0.474 mm; the surface area was reduced by -6.0% and the volume by -3.4%. The root mean square was 0.238 mm and the mean maximum absolute surface deviation was 0.927 mm. The SLM technique showed a high precision with a mean absolute deviation of 0.045 mm and a standard deviation of 0.04 mm. Conclusion: 3D-printed tooth replicas with a very high accuracy could be produced based on CBCT data. The described method is suitable for manufacturing tooth replicas for use in tooth autotransplantations or for fabricating root analogue implants. Keywords: 3D printing, rapid prototyping, selective laser melting, tooth replicas, cone beam computed tomography, autologous tooth transplantation, root analogue implants, implantology

Objectives: To prove the biocompatibility of biomaterials applied in biomedical devices, in vitro testing is crucial to render a material fit for medical application. The material of choice for dental implants is commercially pure titanium (cp-Ti), while other materials such as zirconia and polyetheretherketone (PEEK) are considered highly promising due to their functional and esthetic properties. The aim of this study was to determine whether PEEK with defined mean surface roughness and composition could achieve results equal to titanium or zirconia. Materials and methods: Disks measuring 14 mm in diameter and 1 mm in thickness made from cp-Ti, yttria-stabilized zirconia (Y-TZP), and filled PEEK with a smooth surface finish were used for cell culture experiments. Human fetal osteoblasts (hFOB) were cultured in vitro on each material to observe changes after 1, 3, and 7 days regarding cell viability and lactate dehydrogenase (LDH) release. Additionally, mRNA expression of proliferative factors PCNA and Ki67 and cellular adhesion (vinculin mRNA expression and immunofluorescence staining) were analyzed after 3 days in the culture. Results: In hFOB cultures, adhesion and viability were decreased on PEEK platelets, while LDH release remained stable. No significant difference was observed in cp-Ti and Y-TZP when compared to the control. Conclusions: The performance of cp-Ti and Y-TZP was equal to the control in all tests. It seems that highly polished PEEK in this particular composition cannot be recommended for osseointegrated implant applications due to decreased osteoblast attachment. Further investigations are recommended, especially in surface structures optimized for osseointegration. Keywords: biocompatibility, osteoblasts, polyetheretherketone, PEEK, titanium, zirconia

The aim of the study was to test whether or not, for primary bone augmentation, the use of a xenogenic bone block loaded with rhBMP-2 results in similar bone quantity and quality compared to an autogenous bone block and to evaluate patient morbidity following the surgical procedure with the two treatment modalities. 24 patients requiring implant therapy for the reconstruction of 1 to 4 missing teeth and insufficient bone volume for implant placement were randomly assigned to receive one out of two treatment modalities. Both treatment modalities were successful in regenerating bone to allow for dental implant placement at 4 months. Histologically, a higher amount of mineralised tissue was observed for the control group at 4 months. The use of a second surgical site in the control group tended to a higher patient morbidity compared to the test group, but did not reach statistical significance. Keywords: dental implants, guided bone regeneration, growth factors, bone morphogenetic protein-2, autogenous bone blocks