International Journal of Oral Implantology, 01/2020

Purpose: To assess the technical and biological complications of screw- and cement-retained implant-supported full-arch dental prostheses. Materials and methods: An electronic search was conducted on Medline/PubMed and Cochrane databases in February 2019; irrespective of any time restrictions using MeSH terms. All studies were first reviewed by abstract and subsequently by full-text reading. Further hand search was performed to identify other related references. Articles only related to cement-retained and/or screw-retained reconstructions in full-arch fixed dental prostheses (FDP) were included. Results: The initial literature search resulted in 3670 papers. 3478 articles remained after removing duplicate articles, and 3439 articles were further excluded by the reviewers after the abstract screening, which resulted in a selection of 39 studies. 12 studies were further excluded due to not fulfilling the inclusion criteria. Hand searching resulted in two additional papers being included, and finally, 29 articles were included in this review. Screw-retained full-arch fixed dental prostheses have fewer complications than cemented reconstructions. Biological complications such as marginal bone loss > 2 mm occurred more frequently in cemented reconstructions, and technical complications such as screw-loosening and screw fracture occurred more in screw-retained reconstructions. Conclusion: Cemented reconstructions exhibited more biological complications (implant loss, bone loss > 2 mm) and screw-retained prostheses exhibited more technical problems. Clinical outcomes were influenced by both fixations in different ways. The screw-retained restorations were more easily retrievable than cemented ones, therefore, technical and eventually biological complications could be treated more easily. For this reason, and for their higher biological compatibility, these reconstructions are preferable. Keywords: biological complications, cement-retained, full-arch fixed implant reconstruction, screw-retained, technical complications Conflict-of-interest statement: The authors declare no conflicts of interest. No funding was received for this review.

Purpose: To compare the clinical and radiographic outcomes of platform switching (PS) and regular platform (RP) implants. Materials and methods: This study was designed as a randomised controlled split-mouth trial. Eighteen patients, with bilaterally missing single premolars or molars to be restored with implant-supported single crowns, were consecutively enrolled. Implant sites were randomly assigned to be treated according to the PS concept (PS group), or with matching implant–abutment diameters (RP group). A total of 36 implants were placed in healed bone, with an insertion torque between 35 and 45 Ncm, according to a one-stage protocol. All the implants were loaded with a screw-retained provisional crown 3 months after implant insertion. Definitive screw-retained single crowns were delivered 2 months later. Outcome measures were implant and prosthetic survival rates, biological and prosthetic complications, marginal bone level (MBL) changes, pocket probing depth (PPD) and bleeding on probing (BOP). Clinical data were collected at implant placement (baseline), implant loading (3 months later) and at 9, 36 and 60 months after loading. Results: One patient dropped out after 4 years of follow-up. No implant failed and no prosthetic complications were recorded during the study period. One patient experienced mucosal inflammation with positive BOP (RP group) after 3 months and three patients had bilateral peri-implant mucosal inflammation with positive BOP at 6, 24 and 36 months, respectively. No other biological complications were recorded up to 60 months of follow-up. There were no statistically significant differences between groups for complications (3/18 versus 4/18; P = 1.0). Nine months after loading the mean MBL was 0.93 ± 0.26 mm (95% CI 0.81 to 1.05) for RP implants and 0.84 ± 0.23 mm (95% CI 0.73 to 0.95) for PS implants. No statistically significant difference was observed between the groups (P = 0.18). Thirty-six months after loading, the mean MBL was 1.09 ± 0.31 mm (95% CI 0.95 to 1.24) in the RP group and 1.06 ± 0.24 mm (95% CI 0.94 to 1.17) in the PS group, with no statistically significant difference between groups (P = 0.70). Sixty months after loading the mean MBL was 1.24 ± 0.39 mm (95% CI 1.05 to 1.43) in the RP group and 1.20 ± 0.21 mm (95% CI 1.01 to 1.39) in the PS group, with no statistically significant difference between the groups (P = 0.85). The mean PPD was 2.58 ± 0.58 mm (95% CI 2.32 to 2.84) in the RP group and 2.40 ± 0.72 mm (95% CI 2.21 to 2.59) in the PS group at 60 months follow-up, with no statistically significant difference between the groups (P = 0.49). The mean BOP was 0.90 ± 0.88 (95% CI 0.58 to 1.22) in the RP group and 0.93 ± 0.97 (95% CI 0.51 to 1.35) in the PS group at 60 months of follow-up, with no statistically significant difference between the groups (P = 0.85). Conclusions: Implants restored according to the PS concept and matching implant–abutment diameters showed comparable clinical and radiographic results up to 5 years after loading. Keywords: dental abutment, dental implants, implant–abutment interface, marginal bone loss, platform switching Conflict-of-interest statement: This study was not supported by any company. All the authors declare no conflicts of interest.

Purpose: The aim of this study was to identify factors associated with failure of maxillary and mandibular dental implants before permanent crown placement. Materials and methods: The present study included adults who underwent dental implantation between January 2003 and December 2016. Implant failure before the permanent prosthesis placement was defined as early implant failure. Patients were divided retrospectively into groups according to the status of their implants; ie, a group with no early implant failure and a group with at least one early failure. Patient-related and implant site-related factors were analysed. Results: 18 (4.8%) of the 376 patients had at least one implant that failed early. 49 (4.7%) of the 1,050 implants included in the study failed early. After adjustment, significant risk factors associated with early failure of maxillary implants included age, bone regeneration for insufficient bone, and signs of postoperative infection. In the mandibular implants, the only significant risk factor for early failure after adjustment was postoperative infection signs. Conclusions: The risk factors associated with early implant failure differed between the maxilla and mandible. Early failure was more attributed to these causes than to a difference in morphology or bone quality between the maxilla and mandible. Prospective studies focusing on the interaction between these risk factors are needed. Keywords: complications, early implant failure, implants, sinus elevation, smoking The author declares no conflicts of interest related to this study.

Purpose: To explore risk indicators potentially associated with early apical peri-implantitis (EAP). Materials and methods: A retrospective survey was performed in 2017 with recorded information from patients receiving dental implants between 1996 and 2016. Reporting follows the STROBE (strengthening the reporting of observational studies in epidemiology) guidelines. Data were collected from the medical histories and radiographs: diagnosis of EAP (health/disease), gender, age, type of surgery (immediate/delayed placement), implants placed (position, width, length, location, mesial and distal tooth-implant distance measured at the apex, state of the adjacent tooth and tooth being replaced, and surgical complications. Once the EAP had developed, data were collected regarding days of evolution, symptoms, signs and radiological findings. Results: A total of 2548 patients (57.1% females and 42.9% males) with 8110 implants were enrolled in the study. 46 patients with 58 implants were diagnosed with EAP – 23 in the maxilla (39.6%) and 35 in the mandible (60.4%) – between 6 and 50 days after implant placement, with a mean period of 21.7 days (SD 10.1). The frequency of EAP was 1.81% in patients and 0.71% in implants. Immediate placement multiplied the odds of developing EAP 21-fold (95% CI 6.74 to 65.7; P < 0.001) versus delayed placement. The existence of an apical lesion in the tooth being replaced multiplied the odds of developing EAP 26.3-fold (95% CI 4.24 to 162.8; P < 0.001). Replacing a tooth endodontically treated increased the odds 3.48 times (95% CI 0.99 to 12.3; P = 0.052). The presence of an adjacent endodontically treated tooth increased the odds 0.97-fold (95% CI 0.26 to 3.60; P = 0.963). An apical mesial distance of ≤ 1.5 mm increased the odds up to 5.12-fold (95% CI 2.12 to 12.4; P < 0.001). Conclusions: The presence of endodontic periapical lesions or endodontic treatment in the tooth being replaced, immediate implant placement or mesial tooth-implant distance measured at the apex were significantly associated with increased odds of EAP. Keywords: early apical peri-implantitis, implant failure, implant periapical lesion, retrograde peri-implantitis Conflict-of-interest statement: The authors declare no conflicts of interest in relation to this study.

Purpose: The aim of this study was to estimate bleeding prevalence and postoperative peri-oral purpura after full-arch immediate implant rehabilitation according to the 'All-on-four' technique, in patients on different oral anticoagulant therapies (warfarin and rivaroxaban). Materials and methods: A total of 120 patients (47 women, 73 men, mean age 66.4 years) presented with edentulous or partially edentulous arches. All patients were treated with immediate full-arch fixed prostheses (28 maxillary, 34 mandibular), each supported by four implants (two vertical, two distally tilted). Participants were divided in three groups: 40 patients under treatment with warfarin formed group A, 40 patients under treatment with rivaroxaban composed group B, and 40 healthy subjects composed the control group. As the primary outcome measure, mild, moderate and severe postoperative bleeding was recorded. As the secondary outcome measure, the presence of postoperative petechiae, ecchymoses and haematomas in oral and peri-oral tissues was recorded. Results: Patients under treatment with warfarin (group A) showed a higher prevalence of postoperative bleeding (P = 0.002) and purpura (P = 0.012) in comparison with other groups. No severe bleeding took place and no haematomas appeared in any patient. Prefabricated metal-reinforced, screw-retained, acrylic resin provisional restorations were delivered in all patients. Conclusions: The preliminary results of this prospective case-control study showed how immediate rehabilitation according the 'All-on-four' technique could be a safe and predictable procedure in anticoagulated patients where anticoagulation therapy is not discontinued or modified. Keywords: All-on-four, bleeding, dental implants, rivaroxaban, warfarin Conflict-of-interest statement: The authors declare they have no conflicts of interest.