Purpose: To prospectively assess marginal bone loss and implant survival with Astra Tech (Dentsply Sirona, Charlotte, NC, USA) (group A) and Brånemark (Nobel Biocare, Zurich, Switzerland) (group B) implants in a split-mouth study conducted over a 20-year follow-up period. Materials and methods: A total of 95 implants (n = 50, group A and n = 45, group B) were randomly placed in the left or right side of the maxilla or mandible in 18 patients. Clinical and radiographic examinations were performed, and results were reported at 5, 10, 15 and 20 years after insertion of the prosthesis. Results: Ten patients were followed up for 20 years (n = 26 implants, group A and n = 25 implants, group B). No implant loss or prosthetic failures were observed. After 20 years of follow-up, no significant differences in marginal bone loss were found between both implant groups (P = 0.25). The proportion of marginal bone loss ≥ 0.5 mm was not significantly different between implant types (P > 0.05), and no statistically significant relationships were found between marginal bone loss and time (P ≥ 0.05). More specifically, there was no significant difference in marginal bone level between year 20 and baseline in group A (P = 0.70), whereas a difference of 0.5 to 1.0 mm was found in group B (P = 0.15). Conclusions: After 20 years of follow-up, marginal bone loss around screw-shaped titanium implants was clinically insignificant. Furthermore, no significant differences in survival and marginal bone loss were found between group A and B implants over the follow-up period. Keywords: bone remodelling, implant system, marginal bone level, osseointegration, split-mouth design Conflict-of-interest statement: The authors declare there are no conflicts of interest relating to this study.

Purpose: To assess the fit and cement gap of fixed partial dentures supported by two implants made using conventional and digital workflows. Materials and methods: Patients requiring fixed partial dentures supported by two implants were included in the study. Forty-eight zirconia fixed partial denture bars supported by two implants (AnyOne, MegaGen, Daegu, South Korea) were produced using a conventional (n = 24, group C) and digital (n = 24, group D) workflow. All implants had the same internal connection prosthetic platform. Silicone open tray impressions with splinted copings (group C) and digital impressions using a Trios 3 intraoral scanner (3Shape, Copenhagen, Denmark) (group D) were taken for each patient. The fit and cement gap were assessed by scanning electron microscopy on the verified master cast. The distance between reference points on the titanium base and implant analogue was measured with and without tightening the prosthetic screw. The difference in distance was calculated and represented the misfit (Dmisfit). The cement gap (Dcement) was measured as the shortest vertical distance from the inferior edge of the bar to the top edge of the titanium base. Results: The median Dmisfit values (interquartile range) differed significantly (P < 0.05) between the groups, with 59 (60) µm for group C and 78 (88) µm for group D. Fixed partial dentures fabricated using a digital workflow presented lower Dcement values (35 [26] µm) than the conventional group (38.9 [23] µm) (P < 0.05). Conclusions: Both workflows produced different levels of fit and differently sized cement gaps when measured on the master casts using scanning electron microscopy. A cast-free digital workflow was associated with a smaller cement gap, but larger misfit was detected when measuring on the verified master cast. Keywords: Key words, cement gap, digital impression, implant prosthodontics, passive fit, , ABSTRACT Conflict-of-interest statement: The authors declare there are no conflicts of interest related to this study.

Purpose: To compare radiographic predictors of medication-related osteonecrosis of the jaw in dental extraction sites. Materials and methods: Forty-one oncological patients undergoing intravenous or subcutaneous antiresorptive treatment, with a history of dental extraction visualised by panoramic imaging, were included in this retrospective study. Age-, sex- and extracted tooth–matched healthy patients who had previously undergone panoramic imaging were selected as controls (n = 57). A total of 288 extraction sites were independently evaluated by two oral and maxillofacial radiologists, who assessed eight distinct radiographic features. The radiographic features of extraction sites were noted to allow comparison between and within subjects regarding healing and osteonecrosis development. The association between radiographic findings, underlying dental disease and medication-related osteonecrosis of the jaw was also tested. The level of significance was set at 5%. Results: Patients under antiresorptive treatment presented with widening of the periodontal ligament space, thickening of the lamina dura, sclerotic bone pattern, horizontal bone loss and periapical radiolucency with bone reaction (P ≤ 0.05). Development of medication-related osteonecrosis of the jaw was associated with altered bone pattern, angular bone loss, furcation involvement and unsatisfactory endodontic treatment (P ≤ 0.05). An association between medication-related osteonecrosis of the jaw and previous dental disease was also found, particularly for periapical lesions and endodontic-periodontal disease (P ≤ 0.05). Conclusions: Radiographic predictors of further development of medication-related osteonecrosis of the jaw in extraction sites include heterogeneous bone pattern, angular bone loss and furcation involvement. Extraction sites with underlying bony changes related to endodontic and endodontic-periodontal disease are more prone to development of medication-related osteonecrosis of the jaw. Keywords: bisphosphonates, denosumab, extraction socket, maxillofacial surgery, neoplasms, osteonecrosis, radiology, risk factors, systemic health, tooth extraction Conflict-of-interest statement: The authors declare no conflicts of interest relating to this study.

Aims: To evaluate the diagnostic value of non–nerve-selective MRI sequences in posttraumatic trigeminal neuropathic pain (PTNP). Methods: This study retrospectively analyzed all MRI protocols performed between February 2, 2012 and June 20, 2018 commissioned by the Department of Oral and Maxillofacial Surgery, University Hospitals Leuven. Demographic, clinical, and radiologic data were extracted from the records of patients with an MRI in the context of PTNP. A contingency table was constructed based on the opinions of the treating physician and the radiologist who initially evaluated the MRI. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Results: The sample consisted of 27 women (65.9%) and 14 men (34.1%). The sensitivity and negative predictive value of MRI in PTNP were 0.18 and 0.77, respectively. Artifacts interfered with visualization of a possible cause of the trigeminal pain in 24.4% of MRIs. Almost all artifacts (90%) were caused by metal debris originating from the causal procedure or posttraumatic surgeries. MRI resulted in changed management for PTNP patients only once. Conclusion: The diagnostic value of non–nerve-selective MRI sequences for PTNP is low and has little impact on clinical management. Therefore, there is a need for dedicated sequences with high resolution and low artifact susceptibility for visualizing the posttraumatic injuries of the trigeminal branches. Keywords: magnetic resonance imaging, trigeminal nerve, trigeminal nerve injuries

Purpose: Sinus floor elevation (SFE) and simultaneous implant placement is predictable and reproducible. However, the graft material for the antral cavity remains a topic of debate. Considering the high osteogenic potential of the sinus membrane, most graft materials are generally accepted. This study aimed to assess the outcome of simultaneous SFE and implant placement, using leukocyte- and platelet-rich fibrin (L-PRF) as a sole graft material. Materials and Methods: This study was designed as a single cohort prospective study. Clinical and radiographic measurements (cone beam computed tomography [CBCT]) were performed immediately after implant placement and at abutment connection (6 months later). The amount of newly formed bone was linearly recorded on cross-sectional images. Four measurements (mesial, distal, buccal, palatal) were registered with the axis of the implant as reference. Results: Six lateral and 22 transalveolar SFEs were performed in 26 patients with simultaneous implant placement. Six months after surgery, 27/29 implants were clinically integrated. The mean vertical bone gain was 3.4 ± 1.2 mm and 5.4 ± 1.5 mm for transalveolar SFE and lateral SFE, respectively. The level of the new sinus floor was in all cases in continuation with the apex of the implant, and the peri-implant crestal bone height was stable. Conclusion: L-PRF as a sole graft material during simultaneous SFE and implant placement proved to be a practical, safe, and economical subsinus graft material, resulting in natural bone formation.

Purpose: This report originated from the finding of metal artefacts on magnetic resonance images (MRI) which were not detected on panoramic radiography or cone beam computed tomography (CBCT) imaging. It was hypothesised that drills or implants might release metal particles during surgical procedures in the jawbones. Therefore, the aim was to assess whether dental implants or surgical drills might cause metal debris in the surrounding tissues. Materials and methods: The experiment consisted of a postmortem and an antemortem model. A split-mouth design was carried out in a postmortem fresh frozen cadaver head. In the left mandible only the drill preparation sequence was performed, whereas in the right mandible, the drill sequence was followed by implant placement. Before surgery, the postmortem model underwent a baseline MRI acquisition. A second MRI (MRI2) was acquired after performing the osteotomies on both sides and implant placement on the right side. Finally, the implants were carefully removed, and a final MRI (MRI3) was acquired. Bone blocks containing the implant and osteotomy sites were isolated. For the antemortem model, a fresh frozen cadaver head was selected that already had implants in place. An implant in the anterior maxilla was removed and the surrounding bone block was isolated as well. A histological analysis was prepared for both models. Results: In the antemortem model, histological analysis showed irregular-shaped dark particles near the bone-implant interface consistent with metal debris. Additionally, in the postmortem model, both sites showed metal artefacts on MRI2 and MRI3, and by using a balanced fast field echo sequence, and histological analysis, the suspected particles of metal debris were confirmed on both sides of the mandible. Conclusions: Further studies should investigate the origin and extent of the metal debris following implant placement, as well as its clinical significance, possible risk factors and preventive measures. Keywords: artefacts, dental materials, magnetic resonance imaging, radiology Conflict of interest statement: The authors declare no financial disclosures or conflicts of interest.

The aim of this study was to evaluate the factors influencing the volume of healthy maxillary sinuses by means of cone beam computed tomography (CBCT). The sinus volumes in bilateral CBCT images of healthy maxillary sinuses of patients aged 18 years or older were evaluated using dedicated 3D volumetric software. Differences in volume based on gender, age, sinus side, and dental status were analyzed statistically. The study included 174 healthy maxillary sinuses in 87 patients (60 women and 27 men) aged between 18 to 82 years with a mean age of 29.5 years. There were 73 dentate sinuses and 101 partially dentate or edentulous sinuses. Males had significantly larger maxillary sinus volumes compared to females. Subjects below the median age of 24.3 years had a significantly larger sinus volume than older subjects. There was no difference in sinus volume between left and right sides. When partially dentate and edentulous cases were pooled together and compared to dentate cases, there was no difference in sinus volume. Gender and age influence healthy maxillary sinus volume, while sinus side and dental status do not. Neither tooth loss nor increasing age could be correlated with ongoing pneumatization of the maxillary sinus in the present population. Thus, the reported increase of the maxillary sinus volume over life and following extraction of posterior teeth in the upper jaw might be considered a misconception. To prove this hypothesis, prospective studies comparing sinus volumes using standardized time intervals before and after tooth extraction in the posterior maxilla are needed.

Purpose: To evaluate the feasibility and efficacy of a novel concept of early loaded (ie, within 2 weeks) implant-supported fixed dental prostheses (ISFDP) for patients who underwent mandibular reconstruction. Materials and Methods: All patients requiring mandibular reconstruction between July 2013 and March 2016 at AZ Sint-Jan Brugge-Oostende AV were screened for dental rehabilitation according to the proposed concept. Of 17 patients, 10 were eligible for inclusion. Clinical and radiologic assessments of implant integration and prosthetic survival were performed at 6, 12, 24, and 36 months. Patient satisfaction was assessed prior to and after prosthetic rehabilitation using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaires Core 30 and Head & Neck 35, as well as a visual analog scale. Results: Ten patients received mandibular reconstructive surgery for an oral cavity tumor (n = 6), osteoradionecrosis (n = 3), or medication-related osteonecrosis of the jaw (n = 1). Implants were placed within an average of 6 (2 to 21) months postsurgery in a one-stage procedure. Prosthetic rehabilitation was achieved within 2 weeks in 8 of the 10 patients. Two patients received their ISFDP delayed due to postoperative complications. Implant integration and prosthetic outcome at a maximum of 36 months of follow-up were successful in 7 of the 10 patients. At that time, two patients had passed away, while one patient had the ISFPD removed because of graft necrosis after radiotherapy. Patient satisfaction was high, with significant improvement after dental rehabilitation in comparison to mandibular reconstruction alone. Conclusion: The present concept offers a feasible and fast prosthetic rehabilitation that improves patient quality of life.

The aim of this study was to evaluate the health or pathology of bilateral maxillary sinuses using cone beam computed tomography (CBCT) with a lowdose protocol, and to analyze potential influencing factors. The study included only CBCT scans with complete visualization of bilateral maxillary sinuses. The scans were taken using a medium to large field of view and a low-dose protocol, as indicated by the manufacturer. CBCT images were analyzed with regard to the morphology of the sinus membrane and surrounding bone twice by one observer. Influencing factors such as age, sex, or status of the remaining dentition in the posterior maxilla, including periodontal and endodontic parameters, were evaluated. The study included 134 CBCT scans (268 maxillary sinuses). Using a low-dose protocol, intraobserver reliability of the measurements was almost perfect (kappa value range 0.875 to 1). More than half the sinuses evaluated (63.1%) did not show visible morphologic changes. The most frequently identified pathologic appearance was a flat, shallow thickening of the sinus membrane of > 2 mm (47 positive findings [17.5%]). Only 15 (5.6%) sinuses were associated with teeth with endodontic treatment and/or pathology, and 10 (3.7%) with teeth exhibiting periodontal pathology. CBCT scans with a low-dose protocol can be recommended as a feasible adjunctive tool to evaluate health or pathology of the maxillary sinuses prior to surgical interventions such as sinus floor augmentation. Of all morphologic changes seen, only a small portion of the cases were considered to need further medical diagnosis/treatment.