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Abstract Background Tumorous diseases of the jaw demand effective treatments, often involving continuity resection of the jaw. Reconstruction via microvascular bone flaps, like deep circumflex iliac artery flaps (DCIA), is standard. Computer aided planning (CAD) enhances accuracy in reconstruction using patient-specific CT images to create three-dimensional (3D) models. Data on the accuracy of CAD-planned DCIA flaps is scarce. Moreover, the data on accuracy should be combined with data on the exact positioning of the implants for well-fitting dental prosthetics. This study focuses on CAD-planned DCIA flaps accuracy and proper positioning for prosthetic rehabilitation. Methods Patients post-mandible resection with CAD-planned DCIA flap reconstruction were evaluated. Postoperative radiograph-derived 3D models were aligned with 3D models from the CAD plans for osteotomy position, angle, and flap volume comparison. To evaluate the DCIA flap’s suitability for prosthetic dental rehabilitation, a plane was created in the support zone and crestal in the middle of the DCIA flap. The lower jaw was rotated to close the mouth and the distance between the two planes was measured. Results 20 patients (12 males, 8 females) were included. Mean defect size was 73.28 ± 4.87 mm; 11 L defects, 9 LC defects. Planned vs. actual DCIA transplant volume difference was 3.814 ± 3.856 cm³ (p = 0.2223). The deviation from the planned angle was significantly larger at the dorsal osteotomy than at the ventral (p = 0.035). Linear differences between the planned DCIA transplant and the actual DCIA transplant were 1.294 ± 1.197 mm for the ventral osteotomy and 2.680 ± 3.449 mm for the dorsal (p = 0.1078). The difference between the dental axis and the middle of the DCIA transplant ranged from 0.2 mm to 14.8 mm. The mean lateral difference was 2.695 ± 3.667 mm in the region of the first premolar. Conclusion The CAD-planned DCIA flap is a solution for reconstructing the mandible. CAD planning results in an accurate reconstruction enabling dental implant placement and dental prosthetics.

Abstract Introduction : Amelogenesis imperfecta (AI) is a genetically determined, non-syndromic enamel dysplasia that may manifest as hypoplasia, hypomaturation, or hypocalcification and can commonly be classified into four primary groups. In this retrospective analysis, specific orofacial characteristics are described and associated with each of the AI types based on a patient cohort from Witten/Herdecke University, Germany. Methods Data from 19 patients (ten male and nine female, mean age 12.27 ± 4.06 years) with AI who presented at the Department of Orthodontics between July 2011 and December 2023 were analyzed. Baseline skeletal and dental conditions were assessed, including the presence of hypodontia, displacements, and taurodontism. AI was classified into classes I–IV based on phenotype. Treatment needs were evaluated according to the main findings following the German KIG classification, while the radiological enamel situation was determined using panoramic radiographs. Results An approximately equal distribution between classes II and III was found and a slight inclination toward a dolichofacial configuration (ΔML-NSL: 5.07 ± 9.23°, ΔML-NL: 4.24 ± 8.04°). Regarding orthodontic findings, disturbance in tooth eruption as well as open bite were the most prevalent issues (both 36.8%, n = 7). The most common AI classes were type I and II, which show an almost even distribution about the skeletal classes in sagittal dimension, while dolichofacial configuration was found most frequently in vertical dimension. Conclusion Both clinical and radiological orthodontic findings in context with AI are subject to extensive distribution. It seems that no specific orofacial findings can be confirmed in association with AI with regard to the common simple classes I–IV. It may be more appropriate to differentiate the many subtypes according to their genetic aspects to identify possible associated orthodontic findings.

Abstract Background The aim of this study was to determine the values of different perfusion parameters- such as oxygen saturation, the relative amount of hemoglobin, and blood flow- in healthy subjects compared to patients with gingivitis as a non-invasive measurement method. Methods A total of 114 subjects were enrolled in this study and separated into subjects with gingivitis (50) and without gingivitis (64) based on clinical examination. Gingival perfusion was measured at 22 points in the maxilla and mandible using laser Doppler flowmetry and tissue spectrophotometry (LDF-TS) with the “oxygen to see” device. All patients underwent measurement of gingival perfusion, followed by the clinical evaluation (measurement of probing depths, evaluation of bleeding on probing, plaque level, and biotype). Perfusion parameters were compared between the groups, associations between the non-invasive and clinical measurements were analyzed, and theoretical optimal cut-off values for predicting gingivitis were calculated with receiver operating characteristics. Results The mean oxygen saturation, mean relative amount of hemoglobin, and mean blood flow all significantly differed between the groups with and without gingivitis (p = 0.005, p 40 AU (p

Objectives: This prospective follow-up study aimed to evaluate the stability values of tapered titanium implants inserted into maxilla following ridge augmentation with free iliac bone graft and crestal bone changes up to three years of follow-up. Material and Methods: A total of seven patients with 34 tapered titanium implants in the maxilla with fixed protheses were enrolled in this prospective follow-up study. Patients with previously augmented maxillae using free iliac bone grafts were included. Implant stability was measured (Osstell™) for up to three months of healing. Peri-implant bone resorption was measured using radiographic images taken immediately after implant surgery and after three years. Using a clinical and radiological examination survival and success rates were evaluated. Results: After implant insertion, the stability was 60.93, whereas the stability increased significantly (P = 0.0192) to 64.97 at implant exposure (after 3 months). The mean bone loss around the implants was 1.13 mm after three years. Clinical parameters revealed a mean sulcus depth of 2.76 (1.18) mm and a bleeding on probing score of 0.29 (0.58). The survival rate was 100%, and the success rate was 67.65% at the end of the study. Conclusions: Tapered implants can be used in free iliac bone grafts for fixed dentures. Implant stability values were high after insertion. In terms of a success rate of 67.65%, the patient’s jaw reconstruction indicated a reduced implant success when comparing the data with healthy patients without any augmentation procedures.

Abstract Introduction The most common chromosomal anomaly is Down syndrome/Trisomy 21, which can be associated with varying degrees of intellectual disability and physical malformation. Specific orofacial characteristics regarding orthodontic treatment options and features are described on the basis of a patient collective from the Witten/Herdecke University, Germany. Methods Data of 20 patients (14 boys and 6 girls, mean age: 11.69 ± 3.94 years) who underwent orthodontic treatment between July 2011 and May 2022 were analyzed. Baseline skeletal and dental conditions were assessed, as well as the presence of hypodontia, displacements, and treatment-related root resorptions. The treatment need was evaluated based on the main findings according to the German KIG classification. In addition, treatment success was determined in relation to patient compliance. Results The patient group was characterized predominantly by a class III relationship (ΔANB: −2.07 ± 3.90°; ΔWITS: −3.91 ± 4.33 mm) and a brachyfacial cranial configuration (ΔML-NL: −4.38 ± 7.05°, ΔArGoMe: − 8.45 ± 10.06°). The transversal discrepancy of the dental arch width from maxilla to mandible was −0.91 ± 3.44 mm anteriorly and −4.4 ± 4.12 mm posteriorly. Considering the orthodontic indication groups, the most frequent initial finding and treatment indication represented hypodontia (85%), followed by frontal (75%) and unilateral lateral (35%) crossbite. In 55% of the cases, the teeth had a regular shape, but in 35% a generalized and in 15% an isolated hypoplasia. Only 25% of the patients could be treated with a fixed multiband appliance due to sufficient cooperation. In each of these patients, varying degrees of root resorptions were detected during treatment, and 45% of all treatments had to be terminated prematurely due to a lack of cooperation by patients or parents. Conclusion The extent of dental and skeletal malformations and the high rate of findings requiring treatment in patients with Down syndrome represent a significant indication for orthodontic therapy, which can be well illustrated by the KIG classification. However, this is in contrast to the eventually increased risk of root resorption, with significantly reduced patient cooperation. A compromised treatment outcome and process must be expected. Consequently, the orthodontic treatment must be simple and realistic to achieve fast and therapeutically satisfactory treatment result.

Abstract Background This rat study aimed to evaluate the feasibility of temperature thresholds that affect peri-implant bone cells and morphology and the potential usefulness of thermal necrosis for inducing implant removal for a subsequent in vivo pig study. Methods On one side, rat tibiae were thermally treated before implant insertion. The contralateral side was used as the control group without tempering. Temperatures of 4 °C, 3 °C, 2 °C, 48 °C, 49 °C, and 50 °C were evaluated with a tempering time of 1 min. Energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM) analyses were performed. Results The EDX analysis revealed significant increases in element weights at 50 °C (e.g., calcium, phosphate, sodium, and sulfur; p

Abstract Background The purpose of this study was to evaluate the osseointegration of zirconia and titanium implants in the rat maxilla in specimens under systemic antiresorptive therapy. Materials and methods After 4 weeks of systematic medication administration (either zoledronic acid or alendronic acid), 54 rats received one zirconia and one titanium implants that were immediately inserted in the rat maxilla after tooth extraction. Twelve weeks after implant placement, histopathological samples were evaluated for implant osteointegration parameters. Results The bone-implant-contact (BIC) ratio revealed no significant inter-group or inter-material differences. The distance between the implant shoulder to the bone level was significantly greater around the titanium implants of the zoledronic acid group compared to the zirconia implants of the control group (p = 0.0005). On average, signs of new bone formation could be detected in all groups, although often without statistical differences. Signs of bone necrosis were only detected around the zirconia implants of the control group (p

Background: The high volume of the fasciomyocutaneous anterolateral thigh flaps (ALT) is suitable for the reconstruction of pronounced soft tissue defects. At the same time, harvesting ALT results in a drastic change in thigh shape. Here, we present an optical three-dimensional imaging method for thigh comparison, which can be an objective and reproducible method for evaluating donor sites after ALT harvesting. Methods: In total, 128 thighs were scanned with an optical three-dimensional scanner, Vectra XT ®. Sixty-eight non-operated right and left thighs were compared and served as a control. Sixty thighs were scanned in the ALT group. The average surface area deviations, thigh volume, thigh circumference, and flap ratio to thigh circumference were calculated. The results were correlated with Δthigh circumference and Δvolume of the unoperated thighs of the control group. Results: No significant difference between the thigh volumes of the right and left thighs was found in the control group. Removal of an ALT flap showed a significant (p < 0.007) volume reduction compared to unoperated thighs (2.7 ± 0.8 L and 3.3 ± 0.9 L, respectively). Flap area correlated strongly with the Δthigh circumference (r = 0.66, p < 0.001) and Δvolume (r = 0.68, p < 0.001). Strong correlations were observed between flap ratio and thigh circumference with Δhigh circumference (r = 0.57, p < 0.001) and Δvolume (r = 0.46, p < 0.05). Conclusions: Optical three-dimensional imaging provides an objective and reproducible tool for detecting changes in thigh morphology volume differences after ALT harvesting.

Abstract The purpose of this rat study was to explore the feasibility of in vivo temperature thresholds affecting bone contact at the implant surface. Based on these data, thermal necrosis should be used for implant removal in the subsequent in vivo study. Rat tibiae of 48 animals at one site were randomly treated with heat or cold before implant insertion. Temperatures of 4 °C, 3 °C, 2 °C, 48 °C, 49 °C and 50 °C for a tempering time of 1 min were evaluated. Numerical simulations of the heat source-implant-bone system were carried out. Effects were assessed by histomorphometrical measurements. The results showed that the selected method of direct tempering using a tempering pin was suitable for maintaining a uniform layer around the pin. Starting at warm temperatures of 48 °C and rising to 50 °C, the BIC ratio revealed declining values and a significant difference was observed when comparing 50 °C to the control group (p = 0.03). However, there were no significant variations within the cold temperatures. This study pinpointed temperature discovered that could lead to the thermo-explantation and so that the number of samples used in future studies on temperature-induced bone necrosis can be reduced to a minimum. Significant BIC value reduction was seen at a temperature of 50 °C for 1 min.

Abstract Background The evaluation of bone remodelling and dental root resorption can be performed by histological techniques or micro-computed tomography (micro-CT). The present study aimed to evaluate the relationship between these two procedures in the context of cleft repair in a rat model. Methods The reconstructed maxillae and the orthodontically-moved first molar of 12 rats were analysed for correlations between the histological and radiological findings retrospectively. The alveolar cleft repairs were performed using bone autografts or (human) xenografts. Four weeks after the operation, the intervention of the first molar protraction was initiated and lasted for eight weeks. The newly formed bone and the root resorption lacunae were determined via histology. In the micro-CT analysis, the average change of bone mineral density (BMD), bone volume fraction (BV/TV), trabecular thickness and trabecular separation of the jaw, as well as the volume of the root resorptions were determined. The Pearson correlation coefficient was applied to study the associations between groups. Results Positive correlations were found only between the newly formed bone (histology) and BMD changes (micro-CT) in the autograft group (r = 0.812, 95% CI: 0.001 to 0.979, p = 0.05). The relationship of newly formed bone and BV/TV was similar but not statistically significant (r = 0.691, 95% CI: −0.274 to 0.963, p = 0.013). Regarding root resorption, no significant correlations were found. Conclusions Due to the lack of correlation between histological and radiological findings of bone remodelling and the development of root resorptions, both methods should be combined in this cleft model in rats for a comprehensive analysis.

Abstract Implant outcomes in comparison to a natural tooth in a rat model using systemic alendronate and zoledronate acid drug administrations were assessed. Fifty-four Sprague–Dawley rats were randomly allocated into two experimental groups (drug application of zoledronic acid; 0.04 mg/kg intravenously once a week and alendronic acid; 0.2 mg/kg subcutaneously five times a week) and one control group with 18 animals in each group. Drug delivery was conducted for a period of 4 months. After 4 weeks either a zirconia or a titanium implant was immediately inserted in the socket of the first molar of the upper jaw. In vivo investigations included host inflammatory parameters and the implant survival and success rates for up to 3 months. Material incompatibilities against titanium and zirconia nanoparticles were evaluated in vitro after stimulation of rat spleen cells. In vivo, IL-6 release around titanium implants demonstrated significantly higher values in the control group (p = 0.02) when compared to the zoledronic acid group. Around the natural tooth without drug administration, the control group showed higher IL-6 values compared with the alendronic acid group (p = 0.01). In vitro, only lipopolysaccharide and not the implant’s nanoparticles stimulated significant IL-6 and TNFα production. In terms of the primary aim of in vivo and in vitro IL-6 and TNFα measurements, no implant material was superior to the other. No significant in vitro stimulation of rat spleen cells was detected with respect to titanium oxide and zirconium oxide nanoparticles.

Abstract The aim of this study was to compare the soft tissue predicative abilities of two established programs depending on the surgical technique and amount of displacement. On the basis of 50 computed tomography images, 11 orthognathic operations with differences in displacement distances and technique (maxillary advancement, MxA; maxillary impaction, MxI; mandibular setback, MnS; mandibular advancement, MnA bimaxillary displacement, MxA/MnS) as well as corresponding soft tissue predictions were simulated using the programs Dolphin (D) and ProPlan (PP). For all the soft tissue predictions by the two programs, eight linear and two angular measurements were performed and compared. The simulation of maxillary impaction showed a similar soft tissue behaviour between the two programs. However, differences or divergent behaviours were observed for other procedures. In the middle third of the face these significant differences concerned in particular the nasolabial angle (Ns-Sn-Ls)(5 mm-MA, D: 119.9 ± 8.6° vs. PP: 129.5 ± 8.4°; 7 mm-MnS: D: 128.5 ± 8.2° vs. PP: 129.6 ± 8.1°; 10 mm-MnA D: 126.0 ± 8.0° vs. PP: 124.9 ± 8.4°; 5 mm-MxA/4 mm-MnS, D: 120.2 ± 8.7° vs. PP: 129.9 ± 8.3°; all p

Abstract Background The pandemic has challenged educational institutions to catalyze digitalization and rapidly develop online teaching formats. The aim of the study was to evaluate the teaching offered for oral and maxillofacial surgery at our university during the pandemic and to investigate the students’ perceptions of the current situation. Methods A 38-item questionnaire with five sections (demographic information, lectures, internships, e-learning, and pandemic-related solutions/effects) was created online. Most questions were answered on a 10-point Likert scale, with 1 indicating “fully agree/positive” and 10 indicating “totally disagree/negative.” The remaining questions were either answered with yes/no, percent value, or open-ended text responses. All 3rd-5th year dental students were invited to voluntarily participate and were sent a link by email in a general mail shot. Results A total of 63.7% of the participants had no prior experience with online courses before the pandemic. The students stated that the change from face-to-face to online teaching worked very well in the last two semesters (mean = 2.73, standard deviation = 2.05). Overall, the pandemic had a rather positive influence on the acquisition of theoretical skills and a negative influence on the acquisition of practical skills (p

Abstract Background The aim of the present study was to assess the development of bacterial deposits and morphological parameters around dental zirconia and titanium implants compared with natural teeth during systemic bisphosphonate medication. Materials and methods Fifty-four rats were randomly allocated into one control group and two experimental groups (drug application of zoledronic and alendronic acid), with 18 animals in each group. After 4 weeks of drug delivery, either a zirconia or a titanium implant was immediately inserted. Microbiological analysis conducted 1 week, 8 weeks, and 12 weeks after surgery included total bacterial count and composition measurements. Samples were analyzed in a scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX). Bone cell morphology was analyzed by transmission electron microscopy (TEM). Results One week after surgery, titanium and zirconia implants of the alendronic acid and control group showed a significantly higher bacterial count when compared to natural teeth in rats with zoledronic acid administration (p 0.05). I n the control group, TEM analysis showed that the osteoblasts had a strongly developed endoplasmic reticulum. In contrast, the endoplasmic reticulum of the osteoblasts in drug-treated animals was significantly less developed, indicating less activity. Conclusions Within the limits of this study, neither implant material was superior to the other at 3-month follow-up. With regard to the treatment and complications of patients with bisphosphonates, the implant material should not be an influencing factor. Bisphosphonates can be used in the rat model to reduce not only the activity of osteoclasts but also osteoblasts of the peri-implant bone.

Abstract Background In dentistry, the reporting of panoramic radiographs is particularly challenging, as many structures are depicted in one image and pathologies need to be identified completely. To enhance the learning process for these interpretations, the advantages of the increasingly popular education method of mobile learning could be used. Therefore, this study aimed to determine the effectiveness of learning to report panoramic radiographs using an application (app) on a mobile device. Methods The existing e-learning programme ‘PantoDict’ was further developed into a mobile app with a new training section. Participants of a dental radiology course were divided into two groups, one of which additionally had the chance to practise reporting panoramic radiographs using the app. A test to assess the knowledge gained was conducted at the end of the semester; the course and the app were also evaluated. Results The group that used the app showed significantly better results in the test than the control group (p

An increase in rivaroxaban therapies is associated with increased numbers of postoperative bleeding despite the use of hemostatic sponges, which are currently the gold standard treatment. VIVO has shown promising hemostatic results, favorable tissue properties, and ease of application, although it has not yet been used in the oral cavity. The aim of this study was to evaluate the hemostatic properties of VIVO in the extraction sockets of 31 rodents and compare this to gelatin sponge (GSP) therapy. At rivaroxaban concentrations of 264.10 ± 250.10 ng/mL, 62 extraction sockets were generated, of which 31 were treated with VIVO and 31 with GSP. The duration time, early and late bleeding events, and wound healing score were determined. Histologic examinations of the tissues were performed after 5 days. VIVO presented a longer procedure, 1.26 ± 0.06 min, but a significantly shorter bleeding time, 0.14 ± 0.03 min. There was no difference between the two groups in terms of the severity and timing of bleeding. More minor early bleeding events were observed for GSP. VIVO showed a significantly better healing score, with favorable histological results. In an animal study, VIVO showed promising hemostatic properties after tooth extraction under ongoing anticoagulative therapy.

Abstract To minimize the postoperative risks posed by grafting autologous transplants for cleft repair, efforts are being made to improve grafting materials for use as potential alternatives. The aim of this study was to compare the bone graft quality of different bone substitutes including the gold standard autografts during the healing processes after cleft repair in the context of orthodontic treatment. In 21 Wistar rats, a complete, continuity-interrupting cleft was created. After 4 weeks, cleft repair was performed using autografts from the hips’ ischial tuberosity, human xenografts, or synthetic bone substitutes [beta-tricalcium phosphate (β-TCP)/hydroxyapatite (HA)]. After another 4 weeks, the first molar movement was initiated in the reconstructed jaw for 8 weeks. The bone remodeling was analyzed in vivo using micro-computed tomography (bone mineral density and bone volume fraction) and histology (new bone formation). All the grafting materials were statistically different in bone morphology, which changed during the treatment period. The β-TCP/HA substitute demonstrated less resorption compared to the autologous and xenogeneic/human bone, and the autografts led to a stronger reaction in the surrounding bone. Histologically, the highest level of new bone formation was found in the human xenografts, and the lowest was found in the β-TCP/HA substitute. The differences between the two bone groups and the synthetic materials were statistically significant. Autografts were confirmed to be the gold standard in cleft repair with regard to graft integration. However, parts of the human xenograft seemed comparable to the autografts. Thus, this substitute could perhaps be used as an alternative after additional tissue-engineered modification.

Abstract Conventional anastomoses with interrupted sutures are challenging and inevitably associated with trauma to the vessel walls. The goal of this study was to evaluate a novel alternative adhesive-based suture-free anastomosis technique that uses an intraluminal stent. Overall, 120 porcine coronary vessels were analyzed in an ex vivo model and were examined for their mechanical (n = 20 per cohort) and hydrostatic strength (n = 20 per cohort). Anastomoses were made using the novel VIVO adhesive with an additional intraluminal nitinol stent and was compared to interrupted suture anastomosis and to native vessels. Sutureless anastomoses withstood pressures 299 ± 4.47 [mmHg] comparable to native vessels. They were performed significantly faster 553.8 ± 82.44 [sec] (p ≤ 0.001) and withstood significantly higher pressures (p ≤ 0.001) than sutured anastomoses. We demonstrate that the adhesive-based anastomosis can also resist unphysiologically high longitudinal tensile forces with a mean of 1.33 [N]. Within the limitations of an in vitro study adhesive-based suture-free anastomosis technique has the biomechanical potential to offer a seamless alternative to sutured anastomosis because of its stability, and faster handling. In vivo animal studies are needed to validate outcomes and confirm safety.

Abstract After craniofacial trauma, symptoms like swelling and pain occur. Cooling reduces these symptoms but the optimal cooling temperature for a maximum benefit without adverse effects is unclear. 30 participants were cooled at 10 °C, 15 °C, 20 °C, 25 °C and 30 °C for 30 min. Before cooling and at 15, 30, 45 and 60 min after cooling, the skin blood flow, oxygen saturation (SO) and haemoglobin concentration (Hb) were measured by laser Doppler spectrophotometry at 2 mm and 8 mm depth. The skin temperature was measured, and the participant’s satisfaction was marked on a visual analogue scale. There were significant differences between males and females in the blood flow, SO and Hb (p

Abstract Background Certification of multidisciplinary tumor centers is nowadays seen as the gold standard in modern oncological therapy for optimization and realization of guideline-based therapy and better outcomes. Single cases are reimbursed based on diagnosis-related groups (DRG). We aimed to review efficiency, cost analysis, and profitability following a certification. Methods Tumor board certification at the university hospital Aachen was implemented in 2013. We compared 1251 cases of oropharyngeal cancer treated from 2008 to 2017 before and after certification. For this purpose, several patient characteristics, surgery, and stay-related constants, as well as expenses and reimbursement heights were analyzed statistically. Results Following certification, the total case and patient number, surgery duration, hours of mechanical ventilation, case mix index points, DRG reimbursements as well as the costs increased significantly, whereas days of intensive care unit, amount of blood transfusions, patient clinical complexity level (PCCL) and the overall stay were significantly lowered. No changes were observed for the patient’s age and gender distribution. Also, the predetermined stay duration stayed constant. Conclusions Certification of head-neck tumor centers causes a concentration of more complex cases requiring higher surgical efforts, which can be processed more efficiently due to a higher level of professionalism. Despite their benefits in cancer care, without compensation, centers may be struggling to cover their expenses in a system, which continuously underestimates them.

Abstract Background Orthognathic surgery can be carried out using isolated mandibular or maxillary movement and bimaxillary procedures. In cases of moderate skeletal malocclusion, camouflage treatment by premolar extraction is another treatment option. All these surgical procedures can have a different impact on the soft tissue profile. Methods The changes in the soft tissue profile of 187 patients (Class II: 53, Class III: 134) were investigated. The treatment approaches were differentiated as follows: Class II: mandible advancement (MnA), bimaxillary surgery (MxS/MnA), upper extraction (UpEX), or Class III: maxillary advancement (MxA), mandible setback (MnS), bimaxillary surgery (MxA/MnS), and lower extraction (LowEX) as well as the extent of skeletal deviation (moderate Wits appraisal: − 7 mm to 7 mm, pronounced: Wits 7 mm, respectively). This resulted in five groups for Class II treatment and seven groups for Class III treatment. Results In the Class II patients, a statistically significant difference (p ≤ 0.05) between UpEX and moderate MnA was found for facial profile (N′-Prn-Pog’), soft tissue profile (N′-Sn-Pog’), and mentolabial angle (Pog’-B′-Li). In the Class III patients, a statistically significant differences (p ≤ 0.05) occurred between LowEX and moderate MxA for facial profile (N′-Prn-Pog’), soft tissue profile (N′-Sn-Pog’), upper and lower lip distacne to esthetic line (Ls/Li-E-line), and lower lip length (Sto-Gn’). Only isolated significant differences (p

Abstract Background Local anaesthesia plays a key role in many aspects of a dentist’s work. The required skills to perform anaesthesia successfully are acquired at university. To take advantage of the possibilities for new teaching formats, a blended learning concept for the local anaesthesia course was developed. The aim of the study was to compare the effectiveness of face-to-face, blended and e-learning in teaching in local anaesthesia by assessing students’ knowledge gain, performance of practical skills and satisfaction with the course. Methods All participants (n = 37) were randomly allocated into three groups. After acquiring the theoretical background in the blended learning, e-learning or lecture groups, a test to assess knowledge gain was performed. The performance of the practical skills was assessed in a small-group seminar. Student attitudes were evaluated with a questionnaire. Results The blended group showed significantly better results (mean = 17, SD =1.5) in theoretical knowledge gain than the other two groups (e-learning group: mean = 14.7, SD = 2.2; lecture group: mean = 14.8, SD =2.3). When comparing the results of the clinical skills assessment, there was no significant difference among all three groups (p > 0.017). The participants confirmed a high overall satisfaction with the course, in particular with the blended learning approach. Conclusion This study indicates that blended learning improves the learning outcome for theoretical knowledge in teaching local anaesthesia more than either face-to-face learning or e-learning alone. Furthermore, the blended learning approach is highly appreciated by the students. For acquiring practical skills, this study shows that blended learning is as effective as other teaching methods.

Abstract Background A teaching concept, that takes individual learning and personal belongings into account, is called the “sandwich principle.” This didactic method is an educational concept that alternates consecutively between individual and collective learning phases during a course. This study aimed to prove whether the application of the sandwich principle in lectures increases the learning outcome compared with classical lectures. Methods All participants (n = 64) were randomly allocated into two groups. One group attended a classical face-to-face lecture and the other attended a lecture that was modified according to the sandwich principle, including activating elements. To compare knowledge gain after the lectures, all the participants had to answer a test comprising40 single-choice questions. In addition, the lectures were evaluated. Results Students attending the sandwich lecture had significantly better scores in the test than those who attending the classical lecture (p

Abstract Background This study aimed at comparing bracket placement and excess bonding adhesive depending on different indirect bonding (IDB) techniques and bracket geometries. Methods Four hundred eighty brackets without hook (WOH) and 360 with hook (WH) were placed on 60 plaster models. Three IDB techniques were tested: polyvinyl-siloxane vacuum-form (PVS-VF), polyvinyl-siloxane putty (PVS-putty), and translucence double-polyvinyl-siloxane (double-PVS). PVS-VF and PVS-putty were combined with chemically, and double-PVS was combined with light cured bonding adhesive. Virtual images of models before and after bracket transfer were generated, and computerized images were compared. Linear, angular deviations, and excess bonding adhesive were measured. Results Linear differences between the three groups were obtained for PVS-VF (WH: 1.08, SD 0.50 mm; WOH: 0.86, SD 0.25 mm), PVS-putty (WH: 0.73, SD 0.51 mm; WOH: 0.58, SD 0.28 mm), and double-PVS (WH: 0.65, SD 0.45 mm; WOH: 0.59, SD 0.33 mm) (P

Osseointegration is the basis of successful dental implantology and the foundation of cementless arthroplasty and the osseointegrated percutaneous prosthetic system. Osseointegration has been considered irreversible thus far. However, controlled heating or cooling of dental implants could selectively damage the bone at the bone–implant interface, causing the reversal of osseointegration or “osseodisintegration”. This review compares five methods for implant removal, published as patent documents between 2010 and 2018, which have not yet been discussed in the scientific literature. We describe these methods and evaluate their potential for reversing osseointegration. The five methods have several technical and methodological similarities: all methods include a handpiece, a connecting device for coronal access, and a controlling device, as well as the application of mechanical and/or thermal energy. The proposed method of quantifying the temperature with a sensor as the sole means for regulating the process seems inadequate. A database used in one of the methods, however, allows a more precise correlation between a selected implant and the energy needed for its removal, thus avoiding unnecessary trauma to the patient. A flapless, microinvasive, and bone-conserving approach for removing failed dental implants, facilitating successful reimplantation, would benefit dental implantology. These methods could be adapted to cementless medical implants and osseointegrated percutaneous prosthetics. However, for some of the methods discussed herein, further research may be necessary.

Background and objectives: In oral and maxillofacial operations, the iliac crest is a commonly used donor site from which to harvest bone for augmentation prior to dental implantation or for reconstruction of jaw defects caused by trauma or pathological lesions. In an aging society, the proportion of elderly patients undergoing iliac crest bone grafting for oral augmentation is growing. Although postoperative morbidity is usually moderate to low, the age and health of the patient should be considered as risk factors for complications and delayed mobilization after the operation. The aim of this retrospective study was to evaluate the postoperative morbidity and complications in elderly patients after the harvesting of iliac crest bone grafts for oral surgery. Material and Methods: Data were collected from a total of 486 patients (aged 7–85) who had a surgical procedure that included the harvesting of iliac crest bone grafts for intraoral transplantation. All patients were operated on between 2005 and 2021 in the Department for Oral and Maxillofacial Surgery of the University Hospital in Aachen, Germany. As parameters for postoperative morbidity and complications, gait disturbances, hypesthesia of cutaneous nerves, incision hernias, iliac crest fractures, delayed wound healing, and unfavorable scar formation at the donor site were all evaluated. Results: The study was performed with 485 patients due to the exclusion of one patient as the only one from whom grafts were taken from both sides. When younger and older patients were compared, neither gait disturbances (p = 0.420), nor hernias (p = 0.239), nor fractures (p = 0.239), nor hypesthesia (p = 0.297), nor wound healing delay (p = 0.294), nor scar problems (p = 0.586) were significantly different. However, the volume of the graft was significantly correlated with the duration of the hospital stay (ρ = 0.30; p < 0.01) but not with gait disturbances (ρ = 0.60; p = 0.597). Additionally, when controlling for age (p = 0.841), sex (p = 0.031), ASA class (p = 0.699), preexisting orthopedic handicaps (p = 0.9828), and the volume of the bone graft (p = 0.770), only male sex was associated with the likelihood of suffering gait disturbances (p = 0.031). Conclusions: In conclusion, harvesting bone grafts from the anterior iliac crest for intraoral augmentation is a safe procedure for both young and elderly patients. Although there is some postoperative morbidity, such as gait disturbances, hypesthesia, scar formation, or delayed wound healing at the donor site, rates for these minor complications are low and mostly of short duration. Major complications, such as fractures or incision hernias, are very rare. However, in our study, the volume of the bone graft was associated with a longer stay in hospital, and this should be considered in the planning of iliac crest bone graft procedures.

Magnesium alloys have exhibited a rapid rate of corrosion and thus early implant failure, so this study was designed to investigate the longer-term effects and in particular on wound closure. The aim of the study is to evaluate Mg-Ca-Zn Alloys as promising biodegradable implants in the field of maxillofacial surgery, which have so far never been evaluated for the changing conditions from a saliva to a serum-like environment after wound closure. Magnesium-0.6/calcium-0.8 wt.% zinc alloys were either immersed for 10 days in artificial saliva or 10 days in Hank’s salt solution as control groups. The test group was transferred from artificial saliva to Hank’s salt solution after 5 days in order to simulate wound closure. Corrosion rates were determined by immersion testing. Additional electron microscopy and energy dispersive X-ray spectroscopy (EDX) were performed. Prior artificial saliva exposure led to significantly decreased (p = 0.0272) corrosion rates after transfer to Hank’s solution in comparison to sole Hank’s solution exposure (0.1703 vs. 0.6675 mg/(cm2·day)) and sole artificial saliva exposure (0.3180 mg/(cm2·day)), which both exhibit a strong increase after 5 days. The results were in accordance with the scanning electron microscopy and EDX pictures. Prior saliva exposure could protect from increasing corrosion rates after wound closure. Thus Mg-Ca-Zn Alloys are promising future implant alloys in oral surgery, whereas other surgical fields without saliva exposure have to deal with accelerated corrosion rates after 5 days.

Aim: This in vitro study aimed to evaluate the effects of implant designs on primary stability in different bone densities and bony defects. Methods: Five implant types (tapered-tissue-level, tissue-level, zirconia-tissue-level, bone-level, and BLX implants) were used in this assessment. The implants were inserted into four different artificial bone blocks representing varying bone-density groups: D1, D2, D3, and D4. Aside from the control group, three different types of defects were prepared. Using resonance frequency analysis and torque-in and -out values, the primary stability of each implant was evaluated. Results: With an increased defect size, all implant types presented reduced implant stability values measured by the implant stability quotient (ISQ) values. Loss of stability was the most pronounced around circular defects. Zirconia and bone-level implants showed the highest ISQ values, whereas tissue level titanium implants presented the lowest stability parameters. The implant insertion without any thread cut led to a small improvement in primary implant stability in all bone densities. Conclusions: Compared with implants with no peri-implant defects, the three-wall and one-wall defect usually did not provide significant loss of primary stability. A significant loss of stability should be expected when inserting implants into circular defects. Implants with a more aggressive thread distance could increase primary stability.

Purpose: Very high or low temperatures will lead to bone damage. The objective of this review was to analyze threshold values for thermal bone necrosis. Methods: Histological animal studies evaluating thermal effects on bone necrosis were selected via electronic and hand searches in English and German language journals until 1 November 2019. The outcome measures were temperature-exposure intervals and laser settings effecting bone damage. Furthermore, investigated parameters were the bone-to-implant contact ratios (BIC) and infrabony pockets around dental implants after thermal treatment. For quality assessment of studies, the CAMARADES study quality checklist was applied. Results: A total of 455 animals in 25 animal studies were included for data extraction after screening of 45 titles from 957 selected titles of the MEDLINE (PubMed), The Cochrane Library, Embase and Web of Science search. The threshold values for bone necrosis ranged between 47 °C and 55 °C for 1 min. A threshold value for cryoinsult and laser treatment has not yet been defined. However, temperatures in the vicinity of 3.5 °C produce a histologically proven effect on the bone and in the surrounding tissue. At 50 °C for 1 min, BIC values significantly decreased and infrabony pockets increased. Bone quality had an influence on the outcome, as cancellous bone suffered higher bone damage from thermal treatment compared to cortical bone. Conclusion: No clear threshold value for bone necrosis is available according to the current literature for warm and cold stimuli. More in-depth and clinical studies are required to provide further insights in assessing the potential of thermal necrosis for implant removal.