Evaluation of fibrin, cyanoacrylate, and polyurethane-based tissue adhesives in sutureless vascular anastomosis: a comparative mechanical ex vivo study.

The stability of a microvascular anastomosis is an important prerequisite for successful tissue transfer. Advances in tissue adhesives are potentially opening new avenues for their use in sutureless microsurgical anastomosis, however they have not yet gained clinical acceptance. In this ex vivo study, a novel polyurethane-based adhesive (PA) was used in sutureless anastomoses and its stability compared with that of sutureless anastomoses performed with fibrin glue (FG) and a cyanoacrylate (CA). Stability was assessed using hydrostatic (15 per group) and mechanical tests (13 per group). A total of 84 chicken femoral arteries were used in this study. The time taken to create the PA and CA anastomoses was significantly faster when compared to the FG anastomoses (P < 0.001): 1.55 ± 0.14 min and 1.39 ± 0.06 min, respectively, compared to 2.03 ± 0.35 min. Both sustained significantly higher pressures (289.3 mmHg and 292.7 mmHg, respectively) than anastomoses using FG (137.3 mmHg) (P < 0.001). CA anastomoses (0.99 N; P < 0.001) and PA anastomoses (0.38 N; P = 0.009) could both withstand significantly higher longitudinal tensile forces compared to FG anastomoses (0.10 N). Considering the background of an in vitro study, the PA and CA anastomosis techniques were shown to be similar to each other and superior to FG, due to their stability and faster handling. These findings need to be validated and confirmed in further in vivo studies.

German S3 guideline on the use of dental ceramic implants.

PURPOSE: Based on the excellent long-term data, dental implants made of titanium are considered the international implantological standard for replacing missing teeth. However, ceramic implants made of zirconia (ZrO2) have experienced a renaissance in the last 15 years due to constant innovations in materials and products, with material properties and soft tissue- and osseointegration behavior comparable to those of titanium. However, one limitation concerning ceramic implants is the lack of reliable long-term data, especially in the case of two-piece implant systems. As there is an increasing demand for ceramic implants from practitioners and patients, the German Society for Implantology (DGI) has decided to develop a guideline on the use of dental ceramic implants at the highest available evidence level with the involvement of experts in this field. METHODS: Statements and recommendations were prepared after conducting a systematic literature search and an independent assessment process involving the relevant clinical literature from 2008 to 2021. The adopted recommendations and statements are summarized in this guideline. RESULTS AND CONCLUSIONS: It confirms the feasible use of one-piece zirconia implants as an addendum/alternative to titanium implants. No final conclusion regarding the application of two-piece ceramic implant systems could be drawn on the basis of the existing data, thus its use can only be recommended after the patient has been informed in detail about the lack of long-term clinical data.

The primary stability of two dental implant systems in low-density bone.

Primary stability in low-density bone is crucial for the long-term success of implants. Tapered implants have shown particularly favourable properties under such conditions. The aim of this study was to compare the primary stability of tapered titanium and novel cylindrical zirconia dental implant systems in low-density bone. Fifty implants (25 tapered, 25 cylindrical) were placed in the anterior maxillary bone of cadavers meeting the criteria of low-density bone. The maximum insertion (ITV) and removal (RTV) torque values were recorded, and the implant stability quotients (ISQ) determined. To establish the isolated influence of cancellous bone on primary stability, the implantation procedure was performed in standardized low-density polyurethane foam bone blocks (cancellous bone model) using the same procedure. The primary stability parameters of both implant types showed significant positive correlations with bone density (Hounsfield units) and cortical thickness. In the cadaver, the cylindrical zirconia implants showed a significantly higher mean ISQ when compared to the tapered titanium implants (50.58 vs 37.26; P < 0.001). Pearson analysis showed significant positive correlations between ITV and ISQ (P = 0.016) and between RTV and ISQ (P = 0.035) for the cylindrical zirconia implants; no such correlations were observed for the tapered titanium implants. Within the limitations of this study, the results indicate that cylindrical zirconia implants represent a comparable viable treatment option to tapered titanium implants in terms of primary implant stability in low-density human bone.

The effect of zirconia and titanium surfaces on biofilm formation and on host-derived immunological parameters.

The aim of this study was to analyse the effect of zirconia and titanium surfaces on biofilm formation and host-derived parameters. Studies comparing zirconia and titanium surfaces were selected up to September 1, 2019. The outcome measures were surface roughness, contact angle, bacterial count, bacterial adherence, biofilm thickness, bacterial distribution, and specifically investigated biofilm and specific host-derived immunological parameters. Random-effects meta-analyses of in vitro and in vivo studies were conducted. A total of 39 studies were included for data extraction. In the systematic review data, 10 studies stated that zirconia accumulated less initial oral biofilm parameters, 16 investigations showed negligible inter-material differences, and only one study showed that zirconia attracted the most biofilm. However, in the meta-analysis, the bacterial coverage was found to be significantly superior for zirconia surfaces (P< 0.00001); the other outcome measures did not show any statistically significant differences between zirconia and titanium for the remaining parameters and the studies presented a substantial degree of heterogeneity. Overall, on the basis of the meta-analysis, the current data situation does not allow a clear preference for the use of zirconia or titanium.

Influence of bone density, screw size and surgical procedure on orthodontic mini-implant placement - part A: temperature development.

The aim of this in vitro study was to determine the influence of bone density, orthodontic mini-implant (OMI) size, and the surgical procedure on temperature increase during implant site osteotomy and placement. OMIs of different sizes (2.0×7, 2.3×7, 2.0×11, and 2.3×11mm) were placed in artificial bone blocks of different densities (D1-D4). Optionally, the drilling and insertion angle was 90° or 60° to the bone surface. A total of 640 OMIs were inserted, and predrilling was performed in 320 cases. All insertions were done without irrigation with an axial load of 20N, which resulted in 64 groups. Temperature measurements were performed during implant site preparation and placement using Type-K-thermocouples. Mean temperature increase differed for OMI osteotomy between 1.38°C and 8.75°C and placement between 3.8°C and 18.74°C, respectively. Critical thermal increase was especially reached during placement using long implants. Increasing bone density and implant size (diameter

Immediate dental and skeletal influence of distractor position on surgically assisted rapid palatal expansion with or without pterygomaxillary disjunction.

The outcome of surgically assisted rapid palatal expansion (SARPE) can be affected by pterygomaxillary disjunction (PMD) and the distractor position. In this study, SARPE was performed, with or without PMD, in 20 fresh cadaver heads. Transverse expansion was conducted twice using a bone-borne distractor in the anterior and posterior positions, resulting in four groups (n=10). Cone beam computed tomography scans were completed before and after SARPE to evaluate maxillary changes. A comparative anterior decrease and posterior increase in midpalatal opening resulted from SARPE with PMD combined with a posteriorly placed distractor. Significant differences in the internal transverse changes were found between the two SARPE techniques combined with an anterior distractor at the level of the premolars and molars for alveolar ridge width (P=0.040, P=0.024), and at the level of the molars for the dental crown width (P=0.017) and corresponding tooth cusp width (P=0.018). In contrast, using a posteriorly placed distractor led to a significant difference for tooth cusp width only (P=0.050). No statistically significant differences were found between external transverse changes or between distractor positions. PMD is more important in achieving a more uniform and parallel transverse expansion pattern than the distractor position. However, a posterior distractor seems to intensify the effects of PMD.

Evaluation of a novel osteosynthesis plate system for mandibular defects.

Continuity defects of the jaw can be reconstructed with titanium plates or microvascular bone flaps; osteosynthesis plates are necessary for both. In this study we performed a retrospective review of patients treated with Medartis MODUS® Mandible Trauma/Reco 2.0-2.5, TriLock bridging plates, mandibulectomy and soft tissue free flap or reconstruction with a bony free flap and TriLock mandibular plates from the same system from January 2015 to August 2019. The variables recorded were sex, age, diagnosis, radiotherapy, date of implantation, date of explantation or death of patient, size of mandibular defect, Jewer classification of defect, number of screws used, segments of bony reconstruction, screws per segment, plate exposure, plate breakage, and pseudarthrosis. The bridging plate group consisted of 41 patients, while the mandibular plate group consisted of 24 patients. The percentage of plate exposure was 17.07% for the bridging plate group and 4.17% for the mandibular plate group. Plate breakage was 0 in both groups. Pseudarthrosis was 4.17% in the mandibular plate group. In the bridging plate group, an anterolateral thigh flap covered all exposures. Of 7 plate exposures, 4 were found in a C defect. The complication rate of the investigated plates was lower than the complication rates of other plate systems.

Aesthetic aspects of adjacent maxillary single-crown implants-influence of zirconia and titanium as implant materials.

The purpose of this retrospective survey was to assess the esthetic aspects of adjacent zirconia and titanium implants in the anterior maxillary area. A total of 40 patients and 109 adjacent implants (17 patients with 47 titanium implants and 23 patients with 62 zirconia implants) was included. The primary aim of this survey was to assess the papillary fill (Jemt score). Additionally, further esthetic aspects were assessed. Papillae were fully present (Jemt score 3) around 39.1% of adjacent zirconia implants and 17.4% of adjacent titanium implants (p<0.01). The papilla deficit was significantly higher 1.64 mm (SD 1.35) around titanium compared to zirconia implants 0.92 mm (SD 0.94, p<0.01). The evaluation of the soft tissue recessions revealed no differences between implant materials, whereas titanium implants presented more visible implant shadows (p<0.01). Zirconia implants had more implants with papillae that filled the entire proximal space compared to titanium implants. Furthermore, titanium implants had a greater frequency of visible implant shadowing than the zirconia implants. Esthetic rules such as the interdental contact area and golden percentage rules did not differ significantly between the titanium and zirconia implants.

"Flipped OR": a modified didactical concept for a surgical clerkship in Oral and Maxillofacial Surgery.

The concept of the clerkship at the Department of Oral and Maxillofacial Surgery was modified into a modern and sustainable teaching model with a flipped classroom approach. The aim was to prove whether these changes increased the students' learning success. For the preparation of the clerkship, an e-learning module with 10 chapters was established. Students were supposed to access one chapter ahead of each day's seminar. A test to assess the gain in knowledge was undertaken before and after participation in the clerkship. An evaluation took place after the test. The results of the test after the clerkship were significantly higher than before (p<0.0001). The evaluation showed that the students were highly satisfied with the course in general, and the e-learning module specifically. In particular, the surgical videos helped them to better understand the operative steps. The clerkship at the Department of Oral and Maxillofacial Surgery was modified into a sustainable blended learning concept with a flipped classroom approach. With these developments, the "flipped operating room" was shown to be effective in improving knowledge and competence among undergraduate dental students.

Evaluation of the bactericidal effect of cold atmospheric pressure plasma on contaminated human bone: an in vitro study.

The use of cold atmospheric pressure plasma (CAPP) as a bacterial decontaminant for chronic wounds has shown good results. The purpose of this in vitro study was to evaluate the bactericidal effects of CAPP on the cancellous area of the bone. Sterile glass slides and processed sterile human bone allografts 1, 2, 3, and 4mm thick were used for initial contamination and further CAPP treatment. Each block was contaminated with Staphylococcus aureus suspension on one side. Each slide was turned 180° and treated on the reverse side. The bacterial count in colony-forming units (CFU) was then measured and compared with that of a control group, and the bactericidal effects of CAPP in relation to bone density evaluated. A significant reduction in count was measured between treated and untreated groups (groups A-D: p<0.01 and group E: p=0.04). A strong positive linear relation was found between bone density and the S aureus count (r=0.844, p=0.156). Treatment with CAPP had a bactericidal effect on bone structures with a penetration depth of up to 4mm. It might be used for all diseases involving infected bone, and so extends the existing range of treatments.

Evaluation of alloplastic mandibular reconstruction combined with a radial forearm flap compared with a vastus lateralis myocutaneous flap as the first approach to two-stage rehabilitation in advanced oral cancer.

After continuity resection of the mandible, reconstruction of continuity with a reconstruction plate and soft tissue can be an alternative to immediate osseous reconstruction in patients with advanced oral cancer. We evaluated exposure of the plate in such reconstructions by comparing the results of a radial forearm flap (RFF) with a vastus lateralis myocutaneous flap (VLMF). We also analysed the resection margins and the incidence of secondary osseous reconstructions after one year free from relapse. We retrospectively examined all 48 mandibular reconstructions in which a reconstruction plate and RFF or VLMF had been used between 2007 and 2016. Exposure rates of plates were assessed and local (size and site of resection) and systemic risk factors (age, sex, treatment with radiation, and smoking) evaluated. Reconstruction plates, together with a RFF, were significantly more likely to be exposed than those with a VLMF (p = 0.01). There was significantly more exposure in the RFF group in mandibular defects larger than 6 cm, in contrast to the VLMF group (p = 0.002). Younger age (p < 0.001), lower body mass index (BMI) (p = 0.05) and smoking (p = 0.011) led to more exposure. In seven cases a second operation was necessary due to macroscopically invaded or close margins. Thirty-one patients had no bony reconstruction because of local recurrence, distant metastases, inadequate resection margins, poor general condition, or a second (different) tumour. Exposure of the plate after mandibular reconstruction happens less often with the VLM flap than with the RFF. The two-step approach can be an option in the treatment of advanced oral cancer.

Experimental peri-implant mucositis around titanium and zirconia implants in comparison to a natural tooth: part 2-clinical and microbiological parameters.

The aim of this study was to assess the clinical and microbiological parameters around dental zirconia and titanium implants compared with natural teeth during experimental plaque accumulation. Clinical parameters were evaluated (gingival index, plaque index, bleeding on probing, and probing pocket depth). Microbiological samples were analyzed for total bacterial cell counts, as well as Tannerella forsythia and Prevotella intermedia counts. A statistically significant difference over time was observed in the groups in terms of the gingival index (P<0.001), plaque index (P<0.001), and bleeding on probing (P=0.039). The lowest mean total number of bacterial cells was measured around the teeth, followed by the zirconia implants; the highest values were found around the titanium implants. T. forsythia and P. intermedia values showed significant changes over time and sessions around the titanium implants. Compared to the soft tissues around zirconia implants and the teeth, those around titanium implants developed a stronger inflammatory response to experimental plaque accumulation in terms of the total number of bacterial cells and T. forsythia and P. intermedia values.

Blended learning modules for lectures on oral and maxillofacial surgery.

Over the last couple of years, new teaching methods have been developed and implemented in German universities, but only rarely in dental schools. The aim of this project therefore was to implement students' requests for such methods to be used in dental education. In 2012, based on an analysis of both quantitative and qualitative requirements, we designed a questionnaire for quantitative analysis, and evaluated a series of lectures on oral and maxillofacial surgery. Based on our findings, we then designed a blended learning module that was gradually integrated into the series. In 2017 we again evaluated the lectures, and rated the module. The two evaluations were then compared using a two-sample z-test. The results showed that students were very satisfied with the approach. They were particularly happy with the surgical videos, which were shown during the lectures and also included in the module, as they helped them to understand the surgical technique. Our survey showed that most of the students were using the online learning program and that it was the resource they preferred. Application of a blended learning approach could satisfy the requirements of the new generation of students, and transform traditional lectures into modern, sustainable, and technology-enhanced learning experiences.

Evaluation of peri-implant bone levels and soft tissue dimensions around zirconia implants-a three-year follow-up study.

The aim of this study was to measure bone levels around zirconia implants during follow-up of up to 3 years. Additionally, the effect of clinical contact point positions on the papilla deficit was evaluated. Eighty-one patients with 105 zirconia implants were examined at the 3-year follow-up. Bone levels were measured on the date of implant placement and at 3 months, 1year, and 3 years thereafter. Distances between the first bone-implant contact and the contact point of the crowns and between the bone level at the adjacent tooth and the contact point of the crowns were assessed. The effect of the clinical contact point position on the papilla deficit was also assessed. Significant reductions in the distances between the bone-implant contact and the implant shoulder, as well as the contact point of the crowns, and between the bone level at the adjacent tooth and the contact point of the crowns, were found. A significant association was found between the papilla deficit and the height of the contact point. Implant survival was 100% and implant success was 95.4%. While zirconia implants presented little bone loss up to 1year, significant bone apposition was observed up to 3years. Low contact points correlated with full papillae, whereas high contact points were associated with a papilla deficit.

Dimensions of hard and soft tissue around adjacent, compared with single-tooth, zirconia implants.

Preservation or regeneration of the papilla has always been a challenge around consecutive implants or with implants next to teeth, and many studies have evaluated the papilla's behaviour and patterns based on surgical technique and prosthetic design, though evidence about its behaviour around zirconia implants is scarce. The aim of this study was to evaluate papilla behaviour between implants and teeth (tooth-implant group) and between consecutive implants (implant-implant group). Ninety patients with 122 zirconia implants (Straumann® PURE Ceramic Implant) were examined at the one-year follow up. We measured the effect of the distance: first from the base of the contact point of the crowns to the contact with bone at the implant site (D1); secondly, to the contact with the bone at the neighbouring tooth or implant site (D2); and thirdly on the papillary deficit (D3). In both the tooth-implant group and the implant-implant group, D1 and D2 correlated significantly with the papillary deficit (D3), whereas D2 was the major determinant factor (Spearman's rho=0.60). In both groups, when D1 and D2 were <6mm, the papilla was present every time. The papillary deficit was significantly greater in the tooth-implant group than in the implant-implant group (p=0.048). We conclude that the ideal distance from the base of the contact point to the bone contact at the implant and to the bone contact at the adjacent tooth in both groups is <6mm. The height of the bone on the teeth adjacent to implants has a significant impact on that of the papilla.

Simulation of three surgical techniques combined with two different bone-borne forces for surgically assisted rapid palatal expansion of the maxillofacial complex: a finite element analysis.

Surgically assisted rapid palatal expansion (SARPE) is a common treatment to correct transverse maxillary deficiencies. Finite element analysis was simulated for six designs of SARPE based on a computed tomography scan of a human skull: median osteotomy with palatal (type A) or alveolar ridge (type B) bone-borne force, additional lateral osteotomy with palatal (type C) or alveolar ridge (type D) bone-borne force, and additional pterygomaxillary separation with palatal (type E) or alveolar ridge (type F) bone-borne force. The transverse expansion was about 1.0mm. The distribution of von Mises stress and the displacement were evaluated. The largest stress distribution was after types A and B, followed by types C and D, and finally types E and F. Displacement increased simultaneously. Palatal bone-borne forces (types A, C, and E) led to higher stress distributions in the midface and maxilla, but to a more parallel expansion compared with alveolar ridge-borne forces (types B, D, and F). The largest bony displacements at the midpalatal suture were anterior in all models. Increased weakening of the bony pillar of the facial skeleton and the use of palatal bone-borne forces leads to a decrease in stress distribution in the midface and to a more parallel transverse expansion of the maxilla.

Papilla and alveolar crest levels in immediate versus delayed single-tooth zirconia implants.

The aim of this study was to determine the correlation between the papilla deficit and the distance between the bone crest at the neighbouring tooth and the contact point of the clinical crown (distance 4) for immediate and delayed zirconia implants. This prospective observational study included 78 patients with 82 implants investigated at the 1-year follow-up. Patients received single-unit zirconia implants (Straumann PURE Ceramic Implant with ZLA surface) that were placed using either the delayed (group A) or immediate (group B) protocol after tooth extraction. The distance of the alveolar crest of the neighbouring tooth to the height of the interdental papilla and the absence of the papilla were also assessed. There was a strong correlation between the papilla deficit and distance 4 in group A (Spearman's rho=0.64). However, in group B, only a weak correlation between the two distances was found (Spearman's rho=0.28). A full soft tissue margin was generated when distance 4 was 7-8mm or less. Delayed implant placement showed a critical distance between the alveolar crest at the neighbouring tooth and the contact point of the crown risking a visible papilla deficit of between 7mm and 8mm.

Effects on primary stability of three different techniques for implant site preparation in synthetic bone models of different densities.

Preparation of implant sites affect the primary stability of implants that is necessary for osseointegration. We have investigated the effect on the primary stability of implants of three techniques used to prepare the site for implants in synthetic bone models of different densities. A total of 540 implants of varying diameters (3.3 (narrow), 4.1 (standard), and 4.8 (wide) mm) and lengths (8 or 12mm) were inserted into three artificial bone blocks (the density of which decreased from D2, D3, to D4), and we compared conventional, fully-guided, and condensing preparation of the site. After insertion, primary stability was measured using resonance frequency analysis. There were significant differences between conventional and condensing procedures (p <0.0001 in all cases) and between fully-guided and condensing procedures (p<0.01 in all cases), but there were no differences between fully-guided and conventional procedures when short implants were used, with a standard or wide diameter in low-density bone blocks (D3 and D4). In low-density bone blocks (D3 and D4) wide implants (4.8mm) compared with narrow (3.3mm) resulted in significantly better primary stability (p<0.0001 in all cases). Fully-guided preparation of the implant site is associated with increased primary stability, but is not an alternative to bone condensing. Use of longer or wider implants can increase primary stability, but the effect is less pronounced after bone condensing.