Endodontic and restorative management of an adult with avulsion of multiple teeth: A case report with 5 years and 9 months of follow-up.

Simultaneous avulsion of four or more teeth is a rare event. This case report examines the dental care given to an adult who, during a bicycle accident, experienced the avulsion of a mandibular incisor as well as all of his maxillary incisors. In the immediate aftermath of the accident, four out of the five incisors were located, promptly collected, and stored in a tooth rescue box, all within a 20-min window. Replantation and splinting were performed on the day of the accident. Endodontic treatment involved sequential intracanal dressing with an antibiotic-corticosteroid paste followed by calcium hydroxide prior to root canal obturation. 3 months post-accident, signs of external replacement resorption (ERR) began to appear in all the replanted teeth. The gap created by the missing maxillary central incisor was managed with a three-unit fixed dental prosthesis, despite the onset of ERR in the incisors used as abutment teeth. Regular follow-ups showed a relatively slow ERR progression rate over a span of nearly 6 years. The patient expressed satisfaction with both the esthetic and functional outcomes. This case, marked by multiple avulsions, underscores the importance of immediate and appropriate intervention alongside the imperative for carefully considered long-term management strategies. Given the decelerated bone remodeling rate in adults, ERR generally progresses at a slower pace than in children. Accordingly, this case demonstrates the viability of retaining replanted teeth over the long term, even when these teeth have been subjected to nonphysiological storage for extended durations, a factor known to impede periodontal healing.

Platelet-Rich Fibrin in Oral Surgery and Implantology: A Narrative Review.

Background: The application of blood concentrates has gained popularity in dentistry in recent years. Platelet-rich fibrin (PRF) has been discussed frequently due to a high content of growth factors and the option of chair-side manufacturing in a simple centrifugation process. PRF is free from adjuvants and inexpensive to produce. The number of studies reporting beneficial effects of PRF in various clinical applications such as alveolar ridge preservation, sinus floor elevation, management and prevention of medical-related osteonecrosis of the jaw, third molar extractions, and guided bone regeneration in dentistry has increased recently. However, to date, neither clinical recommendations nor guidelines are available. The present narrative review aims to summarize the level of evidence on the clinical application of PRF within the field of oral surgery and implantology. Summary: A literature search in Pubmed and Medline has identified 34 articles as a basis for this narrative review. The effectiveness of the clinical application of PRF has been analyzed for five indications within dentistry: medical-related osteonecrosis of the jaw, wisdom tooth extraction, guided bone regeneration, sinus floor elevation, and alveolar ridge preservation. The amount of data for third molar extractions, socket preservation, and guided bone regeneration is extensive. Less data were available for the use of PRF in combination with sinus floor elevations. There is a lack of studies with scientific evidence on PRF and medical-related osteonecrosis of the jaw; however, studies positively impact patient-related outcome measures. Most studies report on beneficial effects when PRF is additionally applied in intrabony defects. There is no evidence of the positive effects of PRF combined with bone graft materials during sinus floor elevation. However, some benefits are reported with PRF as a sole filling material. Key Messages: Many recently published studies show the positive clinical impact of PRF. Yet, further research is needed to ensure the validity of the evidence.

Piranha-etched titanium nanostructure reduces biofilm formation in vitro.

OBJECTIVES: Nano-modified surfaces for dental implants may improve gingival fibroblast adhesion and antibacterial characteristics through cell-surface interactions. The present study investigated how a nanocavity titanium surface impacts the viability and adhesion of human gingival fibroblasts (HGF-1) and compared its response to Porphyromonas gingivalis with those of marketed implant surfaces. MATERIAL AND METHODS: Commercial titanium and zirconia disks, namely, sandblasted and acid-etched titanium (SLA), sandblasted and acid-etched zirconia (ZLA), polished titanium (PT) and polished zirconia (ZrP), and nanostructured disks (NTDs) were tested. Polished titanium disks were etched with a 1:1 combination of 98% H2SO4 and 30% H2O2 (piranha etching) for 5 h at room temperature to produce the NTDs. Atomic force microscopy was used to measure the surface topography, roughness, adhesion force, and work of adhesion. MTT assays and immunofluorescence staining were used to examine cell viability and adhesion after incubation of HGF-1 cells on the disk surfaces. After incubation with P. gingivalis, conventional culture, live/dead staining, and SEM were used to determine the antibacterial properties of NTD, SLA, ZLA, PT, and ZrP. RESULTS: Etching created nanocavities with 10-20-nm edge-to-edge diameters. Chemical etching increased the average surface roughness and decreased the surface adherence, while polishing and flattening of ZrP increased adhesion. However, only the NTDs inhibited biofilm formation and bacterial adherence. The NTDs showed antibacterial effects and P. gingivalis vitality reductions. The HGF-1 cells demonstrated greater viability on the NTDs compared to the controls. CONCLUSION: Nanocavities with 10-20-nm edge-to-edge diameters on titanium disks hindered P. gingivalis adhesion and supported the adhesion of gingival fibroblasts when compared to the surfaces of currently marketed titanium or zirconia dental implants. CLINICAL RELEVANCE: This study prepared an effective antibacterial nanoporous surface, assessed its effects against oral pathogens, and demonstrated that surface characteristics on a nanoscale level influenced oral pathogens and gingival fibroblasts. CLINICAL TRIAL REGISTRATION: not applicable.

Treatment alternatives for the rehabilitation of the posterior edentulous maxilla.

Rehabilitation of the edentulous maxilla with implant-supported fixed dental prostheses can represent a significant clinical challenge due to limited bone availability and surgical access, among other factors. This review addresses several treatment options to replace missing teeth in posterior maxillary segments, namely the placement of standard implants in conjunction with maxillary sinus floor augmentation, short implants, tilted implants, and distal cantilever extensions. Pertinent technical information and a concise summary of relevant evidence on the reported outcomes of these different therapeutic approaches are presented, along with a set of clinical guidelines to facilitate decision-making processes and optimize the outcomes of therapy.

The use of Trojan-horse drug delivery system in managing periodontitis.

The aim of this review is to evaluate the possibility of delivering a silver-acid complex via a Trojan-horse mechanism for managing periodontits. We theroised that the complex could be an effective treatment option for bacterial inflammatory processes in the oral cavity. Searches were conducted using MEDLINE, Embase, Web of Science Core Collection, and Google Scholar search engines. We also reviewed several reference lists of the included studies or relevant reviews identified by the search. By using Medical Subject Headings (MeSH) terminology, a comprehensive search was performed for the following keywords: silver, folic acid, periodontitis, macrophages, Trojan-horse mechanism, toxicity, and targeting. Using the keywords mentioned earlier, we selected 110 articles and after appropriate elimination the review was written based on 37 papers. Accordingly the we noted that silver isons were an effective approach to kill oral pathogens. Secondly the Trojan-horse mechanism. could be used by macrophages (as the Trojan horse) to deliver silver ions in large quantities to the inflammatory focus to kill the periodontopathogens. The Trojan-horse mechanism has never been described in the field of dentistry before. The proposed novel approach using the principle of Trojan Horse delivery of drugs/chemicals could be used to manage oral inflammatory conditions. This method can be used to supplement regular treatments.

General and dental injuries sustained at concerts: A questionnaire-based study.

BACKGROUND/AIM: Evidence on the risk of injury at concerts is scant. The aim of this study was to collect data on general and dental injuries incurred by concertgoers in Switzerland and to investigate whether the frequency of accidents was related to music genre, gender and consumption of alcohol. MATERIALS AND METHODS: A questionnaire-based, cross-sectional study comprising 451 concertgoers in Switzerland was conducted on the timeframe January 2019 to February 2021. The survey gathered data on general and dental injuries, alcohol consumption and drug use. The statistical analysis included Fisher's exact tests, chi-squared tests, rank sum tests and logistic regressions (α = .05). RESULTS: There were 28.8% of respondents who reported an injury incurred at a concert. Contusion was the most prevalent injury, accounting for 33.8% of all injuries. Legs were the most commonly injured body part (34.6%). Injuries to their mouth/lips/teeth were reported by 17.7% of respondents. Dental injuries, accounting for 4.6% of all reported injuries, comprised four tooth fractures, one lateral luxation and one avulsion. The risk of injury while attending punk rock concerts was 8.6 times higher than for pop concerts (p < .001). In comparison with pop concerts, metal and rock concerts had an increased risk of injury by factors of 5.1 and 2.3, respectively (p ≤ .029). Neither gender nor drug use had a significant effect on the injury risk (p ≥ .3). Heavy alcohol consumption (>5 standard glasses) increased the risk of injury by a factor of 2.3 (p = .028). CONCLUSIONS: This study suggests that concert attendees at rock, metal and punk concerts face an increased risk of injury, which is likely due to the frequency of aggressive dance styles such as moshing. Heavy alcohol consumption leads to a greater risk of injury at concerts.

Cytokines Activate JAK-STAT Signaling Pathway in MG-63 Cells on Titanium and Zirconia.

Although titanium has been traditionally used as the gold standard for dental implants, recent years have seen the widespread application of zirconia implants given their superiority with regards to reduced bacterial adhesion, inflammation and cellular-interaction in terms of bio-compatibility. The JAK-STAT signaling pathway plays an important role in bone remodeling and formation. The aim of the study was to investigate the activation of the JAK-STAT pathway through different cytokines in osteoblast-like cells (MG-63) on zirconia in comparison to titanium discs. IFN-γ induced the very strong activation of STAT1 protein, IFN-α activated both STAT1 and STAT3 molecules, IL-6 activated STAT3 and IL-4 induced the activation of STAT6 on both surfaces. The activation of STAT proteins was confirmed by western blot, immunofluorescence and flow cytometry using phospho-specific anti-STAT antibodies, which recognize only phosphorylated STAT proteins. The incubation of MG-63 cells with IFN-γ caused the upregulation of MHC class I and class II proteins when MG-63 cells were grown on zirconia and titanium discs. In sum, the present study shows that the JAK-STAT pathway is activated in MG-63 cells when they are incubated on titanium or zirconia surfaces.

Is perioperative antibiotic prophylaxis in the case of routine surgical removal of the third molar still justified? A randomized, double-blind, placebo-controlled clinical trial with a split-mouth design.

INTRODUCTION: Since antimicrobial resistance, caused by various factors including antibiotic overuse and abuse, is a severe challenge, the necessity of perioperative antibiotic prophylactic for surgical third molar removal remains a contentious topic. This study determined whether perioperative antibiotic prophylaxis can reduce surgical site infections (SSIs), swelling, and pain in the case of surgical removal of wisdom teeth. MATERIAL AND METHODS: A randomized, double-blind, placebo-controlled clinical trial with a split-mouth design. A study medication of 2 g amoxicillin, administered 1 h before the third molar removal, followed by 1.5 g each for the first 3 postoperative days, was compared with placebo medication. The primary outcome variable (SSI), secondary clinical parameters (swelling and trismus), and patient-centered outcome measures (bleeding, swelling, pain, and pain medication intake) were documented until postoperative day 7. Statistical analyses were done with a paired t test, t test for independent samples, Chi-square test, and McNemar test, including effect sizes. RESULTS: Primary outcome SSI, in total 11%, and clinical parameters swelling and trismus were not significantly different between the two groups. The patient-centered outcome measures (bleeding, swelling, and pain) did not significantly differ, except for postoperative bleeding in the EG on day 0. No significant result was found with pain medication intake postoperative on days 0-7. CONCLUSIONS: Perioperative administration of oral antibiotics neither revealed additional benefits in patient-related outcome measures nor reduced postoperative complications compared with the placebo group indicated at routine surgical removal of noninflamed wisdom teeth. CLINICAL RELEVANCE: Taking antimicrobial resistance into account, clear recommendations for administering drugs, particularly antibiotics, are critical in oral surgery.

Novel Titanium Nanospike Structure Using Low-Energy Helium Ion Bombardment for the Transgingival Part of a Dental Implant.

AIM(S): The aim of the study was to fabricate a nanospike surface on a titanium alloy surface using a newly established method of low-energy helium ion bombardment. Various methods to achieve nanospike formation on titanium have been introduced recently, and their antibacterial properties have been mainly investigated with respect to Escherichia coli and Staphylococcus aureus. Oral pathogens such as Porphyromonas gingivalis play an important role in the development of peri-implantitis. For that reason, the antibacterial properties of the novel, nanostructured titanium surface against P. gingivalis were assessed, and a possible effect on the viability of gingival fibroblasts was evaluated. MATERIALS AND METHODS: Helium sputtering was employed for developing titanium surfaces with nanospikes of 500 nm (ND) in height; commercially available smooth-machined (MD) and sandblasted and acid-etched titanium disks (SLA) were used as controls. Surface structure characterization was performed through scanning electron microscopy (SEM) and atomic force microscopy (AFM). Following incubation with P. gingivalis, antibacterial properties were determined via conventional culturing and SEM. Additionally, the viability of human gingival fibroblasts (HGFs) was tested through MTT assay, and cell morphology was assessed through SEM. RESULTS: SEM images confirmed the successful establishment of a nanospike surface with required heights, albeit with heterogeneity. AFM images of the 500 nm nanospike surface revealed that the roughness is dominated by large-scale hills and valleys. For frame sizes of 5 × 5 µm and smaller, the average roughness is dominated by the height of the titanium spikes. ND successfully induces dysmorphisms within P. gingivalis cultures following the incubation period, while conventional culturing reveals a 17% and 20% reduction for ND compared to MD and SLA, respectively. Moreover, the nanospike surfaces did not affect the viability of human growth fibroblasts despite their sharp surface. CONCLUSION(S): This study successfully developed a novel titanium-nanospike-based structuration technique for titanium surfaces. In addition, the nanospikes did not hinder gingival fibroblast viability. Enhanced antimicrobial effects for such a novel nanospike-based resurfacing technique can be achieved through further optimizations for nanospike spacing and height parameters.

Esthetic and functional outcomes of narrow-diameter implants compared in a cohort study to standard diameter implants in the anterior zone of the maxilla.

OBJECTIVE: The aim of this study was to evaluate functional and esthetic clinical outcomes and patient satisfaction with narrow-diameter implants in comparison to standard-diameter implants in the anterior zone of the maxilla in a follow-up examination after 1 to 6 years. METHOD AND MATERIALS: The study was designed as a retrospective cohort study investigation including 27 patients receiving a 3.3-mm diameter single implant (NDI, n = 14) or a standard-diameter 4.1-mm single implant in the anterior zone of the maxilla (SDI, n = 16). Descriptive and analytical statistics were performed comparing both groups with regard to clinical examination including esthetic outcome, sulcus fluid flow-rate, crown esthetics, patients' satisfaction on visual analog scales, occurrence of biologic or technical complication, probing pocket depths (Fisher exact test), pink esthetic score (PES) and Periotest (Mann-Whitney U test). The level of significance was set at α = .05. RESULTS: The mean observation period was 4.8 years after crown insertion in the NDI group, and 4.9 years in the SDI group. Significant differences were observed for Periotest values in favor of the 4.1-mm implants (P = .014). No differences were found with regards to esthetics (PES; P = .27) or sulcus fluid flow-rate (P = 0.73) and probing pocket depths (P = .35). Overall patient satisfaction was high for both groups with visual analog scale scores of 9.3 ± 1.1 for NDI and 9.4 ± 1.0 for SDI (P = .39). CONCLUSION: Clinical outcome with narrow-diameter implants was comparable to standard-diameter implants in the anterior zone of the maxilla with similar esthetic assessments and patients' satisfaction.

User Experience and Sustainability of 3D Printing in Dentistry.

BACKGROUND: 3D printing is a rapidly developing technology in the healthcare industry and in dentistry. Its application clearly shows that this area of digital dentistry has potential for everyday usage across all fields, including prosthodontics, orthodontics, maxillofacial surgery, and oral implantology. However, despite gaining ground, there is a lack of information about how specialists (dentists and dental technicians) use additive technology. Our research group aimed to investigate the impact of social media on additive manufacturing technology among dental specialists and their everyday usage of 3D printing. METHODS: This paper investigated specialists' everyday usage of 3D printers via an online survey (Google Forms). The survey questions aimed to discover the number of 3D printers used, the accessibility of the devices, the annual cost, and the design programs. Since specialists tend to build online communities on social media, we circulated our study questionnaire using our profiles on LinkedIn, Facebook, and Instagram platforms during our research. RESULTS: A total of 120 responses were received from 20 countries, with the most significant numbers being from Hungary 23.7% (n = 27), the United States 18.4% (n = 21), and the United Kingdom 7.9% (n = 9). Most of the participants were dentists (n = 68) or dental technicians (n = 29), but some CAD/CAM specialists (n = 23) also completed our survey. The participants had an average of 3.8 years (±0.7) of experience in the 3D printing field, and owned a total of 405 printing devices (3.6 on average/person). CONCLUSIONS: The impact of social media on this research field is growing increasingly. Hence, we support specialists in joining virtual communities on professional platforms. This article intended to provide a practical overview, feedback, and direction for dentists interested in 3D printing technology. From our survey, we can conclude that additive technology is broadening dental applications and the services that we can provide for our patients.

Oral Health Status of Children Living with Type 1 Diabetes Mellitus.

BACKGROUND: Diabetes is a well-known predisposing factor for oral diseases, so prevention in an early age is mandatory. OBJECTIVE: To provide oral screening for children living with type 1 diabetes. We aimed to investigate the oral and general health indexes of T1DM children and compare these data to healthy siblings and controls. METHODS: In this cross-sectional study, 120 DM patients and 78 siblings, thereafter 80 DM children and 95 controls, took part. A detailed questionnaire, panoramic radiographs, and lateral cephalograms were obtained in every orthodontic consultation. We used Pearson's chi-square test for statistical analysis and compared the data of the study and control groups. RESULTS: The oral health values of DM children were significantly better (DMF-T 0.83-1.3) than the national average (3.8-4.5). A total of 75% (n = 60) of the children needed orthodontic treatment for orthodontic or skeletal anomalies. The prevalence of skeletal anomalies was significantly (p < 0.05) higher among patients with diabetes mellitus (DM) than in the control group. The frequency of coeliac disease was significantly elevated compared to any literature data (1-3.5%) in the study (15%) and in the control sibling group (13%). CONCLUSIONS: Co-morbidities such as CD should get more attention as a prognostic factor for a future higher incidence of diabetes. T1DM children can be motivated and health-conscious patients with excellent oral hygiene and dental status. Orthodontic treatment can help eliminate the oral complications of DM. Special diabetes ambulances may help provide oral care for patients with DM.

Effect of a Nanostructured Titanium Surface on Gingival Cell Adhesion, Viability and Properties against P. gingivalis.

OBJECTIVES: The transgingival part of titanium implants is either machined or polished. Cell-surface interactions as a result of nano-modified surfaces could help gingival fibroblast adhesion and support antibacterial properties by means of the physico-mechanical aspects of the surfaces. The aim of the present study was to determine how a nanocavity titanium surface affects the viability and adhesion of human gingival fibroblasts (HGF-1). Additionally, its properties against Porphyromonas gingivalis were tested. MATERIAL AND METHODS: Two different specimens were evaluated: commercially available machined titanium discs (MD) and nanostructured discs (ND). To obtain ND, machined titanium discs with a diameter of 15 mm were etched with a 1:1 mixture of 98% H2SO4 and 30% H2O2 (piranha etching) for 5 h at room temperature. Surface topography characterization was performed via scanning electron microscopy (SEM) and atomic force microscopy (AFM). Samples were exposed to HGF-1 to assess the effect on cell viability and adhesion, which were compared between the two groups by means of MTT assay, immunofluorescence and flow cytometry. After incubation with P. gingivalis, antibacterial properties of MD and ND were determined by conventional culturing, live/dead staining and SEM. Results: The present study successfully created a nanostructured surface on commercially available machined titanium discs. The etching process created cavities with a 10-20 nm edge-to-edge diameter. MD and ND show similar adhesion forces equal to about 10-30 nN. The achieved nanostructuration reduced the cell alignment along machining structures and did not negatively affect the proliferation of gingival fibroblasts when compared to MD. No differences in the expression levels of both actin and vinculin proteins, after incubation on MD or ND, were observed. However, the novel ND surface failed to show antibacterial effects against P. gingivalis. CONCLUSION: Antibacterial effects against P. gingivalis cannot be achieved with nanocavities within a range of 10-20 nm and based on the piranha etching procedure. The proliferation of HGF-1 and the expression levels and localization of the structural proteins actin and vinculin were not influenced by the surface nanostructuration. Further studies on the strength of the gingival cell adhesion should be performed in the future. CLINICAL RELEVANCE: Since osseointegration is well investigated, mucointegration is an important part of future research and developments. Little is known about how nanostructures on the machined transgingival part of an implant could possibly influence the surrounding tissue. Targeting titanium surfaces with improved antimicrobial properties requires extensive preclinical basic research to gain clinical relevance.

Immediate Restoration of Single-Piece Zirconia Implants: A Prospective Case Series-Long-Term Results after 11 Years of Clinical Function.

OBJECTIVES: The aim of this prospective case series was to evaluate single-piece zirconia implants restored with lithium disilicate CAD/CAM crowns through a long-term follow-up. METHODS: In this trial, 20 one-piece zirconia implants were placed in 20 patients. Implants were restored (i) immediately with lithium disilicate CAD/CAM provisionals, and (ii) permanently four months after surgery. Patients were followed for 11 years. Clinical parameters and radiological measurements of the zirconia implants were assessed. For the statistical analysis, paired t-test was applied. RESULTS: Four implants were counted as implant failure due to the loss of implant stability, resulting in a Kaplan-Meier survival rate of 80% up to 11 years. The mean bleeding on probing values were 19.1% (SD ± 13.1) and 18.2% (SD ± 17.6) 96 and 11 years after implant placement, respectively. The plaque index revealed a significant decrease over time (p < 0.001) with a value between 25.9% (SD ± 5.7) and 12.6% (SD ± 10.0) at baseline and 11-years follow-up respectively. The marginal bone level revealed a significant decrease 4, 8, and 11 years after implant insertion (p = 0.001, p = 0.019, and p = 0.027, respectively). CONCLUSIONS: Immediately loaded zirconia single-piece implants showed a suitable success rate in clinical and radiographic outcomes.

Influence of a Novel Drill Design on Heat Generation During Conventional and Guided Implant Osteotomy.

PURPOSE: The aim of this in vitro study was to evaluate the temperature development of a novel, electropolished drill design during conventional and guided implant osteotomy in comparison to conventional drills under standardized conditions. MATERIALS AND METHODS: Single and sequential 12-mm-deep drilling protocols (guided and unguided) with a conventional (control groups) and novel drill (test groups) were performed in artificial bone blocks under external irrigation. Each drilling protocol was repeated 30 times with drill diameters of 2.2, 2.8, 3.5, and 4.2 mm. Temperature changes were recorded by an infrared camera, and the accumulated thermal energy was calculated. For group comparison, a one-way analysis of variance (ANOVA) and Tukey post hoc test were used with a level of significance set to = .05. RESULTS: The highest temperatures were measured up to 77.9°C for small-diameter drills in the control and test groups. The 3.5-mm and 4.2-mm novel drills showed significantly lower heat generation during guided and unguided osteotomy preparation for single and sequential drilling. The accumulated thermal energy during guided osteotomy preparation was significantly lower with the electropolished drills. CONCLUSION: The drill design has an important impact on heat development during osteotomy, which was most pronounced for guided osteotomy with conventional drills and for small-diameter osteotomies.

Status report on dental implantology in Switzerland. An updated cross-sectional survey.

A status report of dental implantology in Switzerland has already been performed in 1994 and 2006. The present study, based on these former surveys, aimed to update these results for the year 2016. To this end, a questionnaire was sent to all dentists in Switzerland who were members of the Swiss Dental Society (SSO) at the time of the survey. The questionnaire asked for personal background data and obtained information about the dentists' knowledge and concepts when using implants, the extent to which they used implants and about specific implant systems, which were selected based on the previous surveys. Out of 3,168 questionnaires, 1,446 were returned (return rate: 45.6%). Approximately 91% of the responding dentists had a practical involvement in implantology (implant placement only, superstructure insertion only, or both). Just over half of them (53%) placed more than twenty implants per year. Good handling was chosen by all dentists (100%) as a selection criterion for the implant system they used preferably. The current data suggested that the range of indications had widened, yet that the edentulous mandible was still the indication of choice. The percentage of dentists engaged in dental implantology doubled from 1994 to 2006 (1994: 42.2%, 2006: 82.2%). An increase of almost 10% in dentists involved in dental implantology was also apparent from 2006 to 2016 (2006: 82.2%, 2016: 91%). Our data show that, whilst the relative number of implant users had greatly increased among Swiss dentists, their rationale to place implants has remained similar.

Stability of screw-retention in two-piece zirconia implants: An in vitro study.

OBJECTIVES: To compare the stability of a screw-retained connection in a novel two-piece zirconia implant to a conventional titanium-based connection in an in vitro chewing simulation including artificial ageing. MATERIAL AND METHODS: Incisor (I) and molar (M) shaped monolithic zirconia crowns were screw-retained on either two-piece zirconia (test) or two-piece titanium (control) implants resulting in 4 groups of 8 samples (titanium implants with incisor-shaped crowns (T-I), titanium implants with molar-shaped crowns (T-M), zirconia implants with incisor-shaped crowns (Z-I) and zirconia implants with molar-shaped crowns (Z-M). These were subjected to artificial ageing by thermal cycling (TC: 2 × 3000 × 5°C/55°C cycles of 2 min) and mechanical loading (ML: 1.2 × 106 cycles of 50 N, f = 1 Hz). Surviving samples additionally underwent a fracture force test. Kaplan-Meier plots were drawn, and two-way ANOVA was calculated taking anatomical localisation and material variables as factors. RESULTS: The mean corresponding survival times were lower for T-M (0.86 × 106  ± 0.31 × 106 cycles) and Z-I (0.84 × 106  ± 0.21 × 106 cycles) compared to T-I (1.14 × 106  ± 0.10 × 106 cycles) and Z-M (1.20 × 106  ± 0.10 × 106 cycles). In one-way ANOVAs for survival time dependent on either location or material, no statistically significant differences could be found (location: p = .31; material: p = .62) in one-way ANOVAs. The interaction of location and material showed significant differences (F = 21.3, p < .001). CONCLUSION: The connection of the tested screw-retained zirconia crowns in two-piece zirconia implants is comparable to standard titanium implants in the specific in vitro testing.

Fully Digitally Guided Implant Surgery Based on Magnetic Resonance Imaging.

PURPOSE: The purpose of this study was to evaluate whether fully digitally guided implant surgery may be performed with sufficient accuracy based on printing virtually designed templates after matching a surface scan with the magnetic resonance imaging (MRI) dataset mimicking edentulous cases based on cadaver maxillae of pigs. MATERIALS AND METHODS: The palatal mucosa of five young pig cadavers was scanned with an intraoral scanner. High-resolution MRI of the jaws was performed, and the images were exported as DICOM files and uploaded into software for implant planning. Six implant osteotomies were virtually planned in each jaw. The intraoral surface scans were fused with the volumetric MRI data based on the palatal soft tissue, and virtual templates for guided implant surgery were created and exported as STL files. These were printed and the templates were used to perform flapless guided osteotomy, with the templates fitting on the soft tissue of the jaws alone. Cone beam computed tomography (CBCT) of the jaws was performed after osteotomy. These data were fused with the virtually planned osteotomies, and the 3D crestal, apical, and axial deviations between the virtually planned and physically performed osteotomies were determined. RESULTS: Matching the surface scans with the mucosa was possible in three cases automatically; additional manual corrections were necessary in two cases. Thirty osteotomies were performed by applying the printed mucosa-supported templates. The mean angular deviation between the planned and realized cavities was 3.29 degrees (0.3 to 11.1 degrees; SD = 2.5 degrees), the mean 3D apical deviation was 1.3 mm (0.22 to 3.98 mm; SD = 0.94 mm), and the mean crestal deviation was 1.76 mm (0.39 to 3.79 mm; SD = 0.88 mm). CONCLUSION: MRI in combination with the presented workflow may be used in edentulous cases for guided implant surgery. Further studies are needed to prove the promising accuracy of this alternative approach in clinical trials.

Comparison of heat generation between guided and conventional implant surgery for single and sequential drilling protocols-An in vitro study.

OBJECTIVES: The aim of this in vitro study was to compare the heat generation during guided osteotomy preparation (GOP) with that of a conventional approach (CA) for a single and sequential drilling protocol. METHODS: Temperature measurements were performed during standardized osteotomy preparations in polyurethane foam blocks with an infrared camera. The four groups included single and sequential drilling with and without the use of a surgical guide. In the first group (single CA) and the second group (single GOP), only the final drills diameters were applied once. In the third group (sequential CA) and the fourth group (sequential GOP), two to four drills with increasing diameters were applied. Guided and conventional as well as single and sequential drilling were compared using a one-way ANOVA with Tukey post hoc test. The level of statistical significance was set at α = 0.05. RESULTS: Guided osteotomy preparation showed statistically significant higher temperatures than CA for the 2.2 mm, the 3.5 mm, and the 4.2 mm drill (p = 0.032, p = 0.005 and p < 0.001, respectively). Sequential drilling led to higher heat generation and longer duration of latent heat than single drilling. For all drilling procedures, the duration of heat exposure over critical temperature was less than 1 min, except for the sequential GOP drilling protocol with the 4.2 mm drill (76 s). CONCLUSIONS: Guided drilling requires specific attention to heat development. When guided implant surgery is performed, a single drilling procedure could alleviate heat production compared to a sequential procedure.

Membrane perforation rate in lateral maxillary sinus floor augmentation using conventional rotating instruments and piezoelectric device-a meta-analysis.

OBJECTIVES: Maxillary sinus augmentation (MSA) is a successful and predictable intervention with low complication rates. Perforations of the Schneiderian membrane may occur impairing the general success. The aim of this study was to compare the incidence of membrane perforations between conventional rotating instruments and piezoelectric devices in a meta-analysis. MATERIAL AND METHODS: An electronic research on MEDLINE and PubMed database was performed evaluating the literature from 1980 till 2016. Meta-analysis was performed with the studies matching the inclusion criteria. The incidence of perforations between conventional and piezo during the lateral maxillary sinus floor elevation was determined, and forest plots and a t test for significance analysis were performed. RESULTS: The search provided 377 articles of which 69 could be included. Selected non-randomised and non-controlled prospective and retrospective studies were incorporated. Conventional rotary instruments were associated with a perforation rate of 24%, the piezoelectric devices with 8% with statistically significant difference between both modalities (p < 0.05). CONCLUSION: Membrane perforations in MSA may be significantly reduced applying piezoelectrical devices for MSA.