Assessment of Dental Student Satisfaction after Internships in Collaborative Dental Practices in Saxony-A Retrospective Questionnaire Analysis.

The goal for dental students of a university-based program should be to learn about practice procedures in a dental office as part of their studies in order to gain insight into day-to-day activities, such as organizational management, patient communication, and problem-solving strategies. All dental students from the Faculty of Medicine at the University of Dresden in Germany, who completed a one-week internship in an external dental office in the last year before taking the final exam, were invited to participate in the survey (total n = 182 in years 2017-2019 and 2022). After completing the internship, the students were asked to anonymously rate the distinctive competencies they had acquired during their dental studies in terms of clinical and social communication skills. The results of the survey showed a good practicability of the acquired dental knowledge and a general satisfaction of students during their internships. No significant influence of the COVID-19 outbreak and the resulting special regulations in dental practices during the pandemic on student satisfaction was found. Students were more satisfied with their completed internships in smaller cities. Therefore, a stronger inclusion of practices outside the big cities should be considered in the current implementation of the new Dental Licensure Act in Germany.

The influence of hydrothermal fatigue on the clinically relevant functional properties of conventional glass-ionomer cements.

During their everyday service, the restorative dental materials are subjected to temperature changes which can be viewed as intensive in the context of the highest allowed temperatures for these materials. In this work, the effect of hydrothermal fatigue on the in vitro tribological performance, compression strength, microhardness, and surface roughness of glass-ionomer cements was studied. Samples of 3 commercially available cements were divided into the reference (aged 14 days) and thermocycled (20,000 cycles; 5-55 °C) groups. The results obtained show that functional properties of the specimens subjected to thermal fatigue significantly differ from the literature data on the cements aged at constant temperatures. The effect of hydrothermal fatigue on the functional properties of cements is discussed in the context of processes induced by exposure to variable temperatures.

Common therapeutic approaches in sleep and awake bruxism - an overview.

Bruxism, a common medical condition characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible, can occur during sleep, when it is known as sleep bruxism (SB), or during wakefulness, when it is known as awake bruxism (AB). Although bruxism often causes headaches, temporomandibular joint pain, masticatory muscle pain, mechanical tooth wear, prosthodontic complications and cracked teeth, there is still not enough data to define and support a standardised approach to its treatment. The aim of this review was to present the pathophysiology, consequences, types and treatment methods of bruxism in order to increase readers' knowledge of this topic. Differences between awake and nocturnal bruxism are included, as well as risk factors and indicators visible during the clinical examination of affected patients. Among the causes we consider are genetics, stress, oral parafunctions and changes in the Central Nervous System (CNS). Potential and common methods of treatment are presented, along with suggested guidelines that should be followed when determining an appropriate treatment method. We draw attention to the notably dynamic development of bruxism in today's society and the importance of informational and preventive projects, especially those targeted at high-risk patients as well as those targeted at specialists, in order to better tackle the bruxism 'epidemic'.

Anatomical journals as publication platforms for dental research.

For the benefit of medical and dental patients, there is a great need for international knowledge exchange, intensive cooperation between basic science and clinical experience and the integration of new research results into everyday practice. Equally important, however, is the interdisciplinary exchange of knowledge between medical professionals, dentists and researchers. So far, it has been more of a standard that certain disciplines, such as anatomy, cell biology, urology, dentistry, etc. published in special trade journals and thus usually only read by certain specialists. This is actually no longer up-to-date. For this reason, the anatomical journal Annals of Anatomy has firmly established itself as an interdisciplinary publication medium. In order to make the latest dental research results accessible to an interdisciplinary specialist audience, the special issue "Dentistry" has become a fixed component of the peer reviewed Journal "Annals of Anatomy" over the past 10 years presenting new results in bone and gingival regeneration, implant and aesthetic dentistry as well as dental and maxillofacial anatomy. In this review, all previously published dental studies were summarized, interpreted and the most important conclusions worked out. This was intended to emphasize the importance of dental research, also with regard to interdisciplinary issues.

Assessment of the Socioeconomic Status and Analysis of the Factors Motivating Patients to Apply for Prosthetic Treatment by Students of Dentistry at the Poznan University of Medical Sciences.

This study aimed to determine the motives for undertaking prosthetic treatment at the Prosthetics Clinic of the Poznan University of Medical Sciences (PUMS), pursued by fifth- and sixth-year medicine and dentistry students. The survey consisted of 18 questions, of which 1 to 11 concerned general patient data, while questions 12 to 18 concerned prosthetic treatment. The only open question in the questionnaire was one regarding the motives for the decision to receive treatment. The study group consisted of 153 patients (102 women-66.67% and 51 men-33.33%) of the Prosthetic Clinic. After collecting a total of 200 questionnaires, rejecting 47 (23.50%) due to the lack of answers to all questions (other than question 18), a total of 153 completed (76.50%) questionnaires were obtained. The main motivating factors for patients to undertake prosthetic treatment are functional and aesthetic considerations. In addition, it turned out, that the authority of the university unit is of greater importance than financial issues. Additionally, some patients undergo treatment by students because they can see positive aspects in it, both for them and for students. Hence, the evaluation of the treatment provided by students, as well as their communication skills and their attitude, are rated very highly, although, again, the evaluation was influenced by the education level.

Survey of student attitudes toward digital technology in practical technical dental education using the AR-Demonstrator-App.

PURPOSE/OBJECTIVES: More and more creative applications are used in the field of dentistry for clinical practice, patient orientation, teaching, and learning, in order to awake the students' interest and to enable a deep learning and its retention. The aim of this study was to demonstrate the impact and the effectiveness of the current simulation laboratories on the practical dental education. For this purpose, a survey on a new developed "AR-Demonstrator-App" was conducted during the orthodontic technical courses in 2017, 2018, and 2020 in the Department of Orthodontics (C.G. Carus, TU Dresden, Germany). METHODS: With this application, the students had the opportunity to see every single step with instructions on how to manufacture a removable orthodontic device in a compulsory technical course. At the end of these courses, the students were asked to anonymously fill out a printed questionnaire with 12 questions regarding the learning progress related to the app. RESULTS: The yearly mean Likert scores and their bootstrapped 95% confidence intervals as well as the yearly median Likert scores suggest a very positive feedback about the use of the new application as an educational instrument. Despite the recognized predominant benefits of this app, the students concluded that they do not prefer the total replacement of the physical plaster casts and that a combination of conventional and computer-based education provided the optimum approach to acquisition of dental practical skills. CONCLUSIONS: This survey indicates a generally positive attitude toward computer-assisted simulation systems, providing the facility for acquisition of knowledge and practical skills in a multimedia environment.

Polymorphic variants in genes related to stress coping are associated with the awake bruxism.

BACKGROUND: Chronic stress is one of the leading predisposing factors in bruxism aetiology, but the influence of genetic factors is also suggested. We aimed to study whether sequence variants in genes involved in stress regulation pathways: NTRK2 and BDNF, may be associated with awake bruxism susceptibility, clinical presentation, and patients' perceived stress level. METHODS: The study group included 104 patients with probable awake bruxism and 191 population controls. Patients underwent dental examination concerning the symptoms of bruxism and psychological testing. Genotyping was performed using HRMA and sequencing. Statistical analyses were conducted, and P values below 0.05 were considered statistically significant. RESULTS: We observed a positive correlation of measured stress level and pathological teeth attrition in the anterior segment (r = 0.45, P < 0.001), enamel attritions (r = 0.44, P < 0.001), tongue impressions (r = 0.50, P < 0.001) and posterior teeth attrition (r = 0.27, P = 0.005). Moreover, the c.196A variant (p.66Met) of the BDNF gene and c.1397-31392G allele of the NTRK2 gene were present with elevated frequency, comparing to controls. CONCLUSIONS: This study hence the thesis that perceived stress level is a substantial contributing factor to awake bruxism occurrence and its clinical manifestations. Moreover, sequence variants in genes related to stress coping may be correlated with awake bruxism's susceptibility via elevated perceived stress level.

Histological evaluation of extraction sites grafted with Bio-Oss Collagen: Randomized controlled trial.

The combination of bovine bone matrix with collagen shows good results in bone and volume preservation after tooth extraction. To determine the ideal time to apply an implant after augmentation with Bio-Oss Collagen and to observe if there are differences in the age of the patients and the sex, the aim of this randomized controlled clinical trial was to compare the post-extraction changes in angiogenic and osteogenic aspects during spontaneous bone regeneration with those during socket preservation using Bio-Oss Collagen. Sixty-six patients were included in this study. After 8-12 weeks, bone biopsies were embedded in paraffin and histological and immune-histological investigated. Using qRT-PCR bone (Alpl, Bglap, Runx2) and angiogenic markers (VEGF, caveolin-1) were identified. The histomorphometric analysis of all examined samples showed no differences between treated and untreated sockets, but a tissue compression. After classification in bone regeneration stages, more samples with woven bone were present in treated sockets than in controls. The Alpl expression correlates with increase in mature bone tissue. In treated sockets a significant decrease in CD34 and caveolin-1 protein expression was found. Additionally, a significant increase of Runx2 and VEGF mRNA was detected in patients younger than 50 years. Thus, all specimens showed ossification in different stages after eight weeks of healing. The treated group gives an earlier stage of ossification than controls, but produces densified tissue with greater volume fraction. It can be assumed that successful implant placement in Bio-Oss Collagen augmented extraction sockets is possible after eight weeks of bone healing.

Influence of botulinum toxin A on craniofacial morphology after injection into the right masseter muscle of dystrophin deficient (mdx-) mice.

BACKGROUND: Severe craniofacial and dental abnormalities, typical for patients with progressive Duchenne muscular dystrophy (DMD), are an exellcent demonstration of Melvin L. Moss "functional matrix theory", highlighting the influence of muscle tissue on craniofacial growth and morphology. However, the currently best approved animal model for investigation of this interplay is the mdx-mouse, which offers only a limited time window for research, due to the ability of muscle regeneration, in contrast to the human course of the disease. The aim of this study was to evaluate craniofacial morphology after BTX-A induced muscle paralysis in C57Bl- and mdx-mice, to prove the suitability of BTX-A intervention to inhibit muscle regeneration in mdx-mice and thus, mimicking the human course of the DMD disease. METHODS: Paralysis of the right masseter muscle was induced in 100 days old C57Bl- and mdx-mice by a single specific intramuscular BTX-A injection. Mice skulls were obtained at 21 days and 42 days after BTX-A injection and 3D radiological evaluation was performed in order to measure various craniofacial dimensions in the sagittal, transversal and vertical plane. Statstical analysis were performed using SigmaStat®Version 3.5. In case of normal distribution, unpaired t-test and otherwise the Mann-Whitney-U test was applied. A statistical significance was given in case of p ≤ 0.05. RESULTS: In contrast to C57Bl-mice, in mdx-mice, three weeks after BTX-A treatment a significant decrease of skull dimensions was noted in most of the measurements followed by a significant increase at the second investigation period. CONCLUSIONS: BTX-A can induce changes in craniofacial morphology and presumably partially inhibit muscle regeneration in mdx-mice, but cannot completely intensify craniofacial effects elicited by dystrophy. Further research is necessary in order to fully understand muscle-bone interplay after BTX-A injection into dystrophic muscles.

Histological features of masticatory muscles after botulinum toxin A injection into the right masseter muscle of dystrophin deficient (mdx-) mice.

OBJECTIVE/BACKGROUND: The most frequently used animal model for human DMD (Duchenne muscular dystrophy) research is the mdx mouse. In both species, characteristic histological changes like inflammation, muscle fiber degeneration and fibrosis are the same, but in contrast to humans, in mdx mice, phases of muscle fiber degeneration are compensated by regeneration processes. AIM: Therefore, the interest of this study was to evaluate histological features in masticatory muscles after BTX-A injection into the right masseter muscle of wild type and dystrophic (mdx) mice, illustrating de- and regeneration processes induced by this substance. MATERIAL AND METHODS: The right masseter muscle of 100 days old healthy and mdx mice were selectively paralyzed by a single intramuscular BTX-A injection. Masseter as well as temporal muscle of injection and non-injection side were carefully dissected 21 days and 42 days after injection, respectively, and fiber diameter, cell nuclei position, necrosis and collagen content were analyzed histomorphologically in order to evaluate de- and regeneration processes in these muscles. Statistical analysis was performed using SigmaStat Software and Mann Whitney U-test (significance level: p < 0.05). RESULTS: At both investigation periods and in both mouse strains fiber diameter was significantly reduced and collagen content was significantly increased in the right injected masseter muscle whereas fiber diameters in mdx mice were much smaller, and these differences were even more apparent at the second investigation period. Necrosis and central located nuclei could generally be found in all mdx mice muscles investigated with an amount of centronucleation exceeding 60%, and a significant increase of necrosis six weeks after injection. In wild type mice central located nuclei could primarily be found in the treated masseter muscle with a portion of 2.7%, and this portion decreased after six weeks, whereas in mdx mice a decrease could also be seen in the non-injected muscles. In contrast, in wild type mice necrosis was not apparent at any time and in all muscles investigated. CONCLUSION: From our results it can be concluded that in mdx mice masticatory muscles de- and regeneration processes were extended, triggered by a selective BTX-A injection, or mdx mice at this age, independently of BTX-A treatment, went through another cycle of de- and regeneration as a characteristic of this disease.

Expression rate of myogenic regulatory factors and muscle growth factor after botulinum toxin A injection in the right masseter muscle of dystrophin deficient (mdx) mice.

BACKGROUND: The mdx mouse, the most approved animal model for basic research in Duchenne muscular dystrophy (DMD), has the ability to compensate muscle degeneration by regeneration process, which is obvious at approx. 3 months of age. Hence, this mouse model is only temporarily suitable to proof craniofacial changes which are usually evident in humans with the progression of the disease. OBJECTIVES: The purpose of our study was to examine the impact of botulinum toxin A (BTX-A) in influencing muscle regeneration in the masticatory muscles of healthy and mdx mice. MATERIAL AND METHODS: Chemo-denervation of the right masseter muscle was induced in 100-day-old, healthy and dystrophic mice by a specific intramuscular BTX-A injection. Gene expression and protein content of myogenic regulatory factors and muscle growth factor (MyoD1, myogenin and myostatin) in the right and left masseter, temporal and the tongue muscle were determined 4 and 21 days after injection, respectively, using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot technique. RESULTS: The 4 day and 21 day interval proved significant but varying changes of mRNA expression in both control and mdx mice. At the protein level, myogenin expression was increased in the temporal and masseter muscle on the injection side in controls, whereas dystrophic mice showed the same effect for MyoD1 expression. Additionally, increased protein expression of all studied genes could be found in dystrophic mice compared to controls, except the left temporal and the tongue muscle. CONCLUSIONS: Muscle regeneration is not constant in BTX-A injected mdx masticatory muscles, presumably due to the already exhausted capacity or functional loss of satellite cells caused by dystrophin deficiency, and, therefore, disturbed regeneration potential of myofibrils. Botulinum toxin A injection cannot fully break down regulatory processes at molecular level in 100-day-old mdx mice. Further investigations are necessary to fully understand the regeneration process following BTX-A injection into dystrophic muscles.

Histological examinations of the in vivo biocompatibility of oxycellulose implanted into rat skeletal muscle.

BACKGROUND: Recently it was shown that oxycellulose suppressed bone regeneration led to an accumulation of connective tissue as well as foam cells in bone defects. OBJECTIVES: Since oxycellulose can be used as a hemostatic agent in general and dental surgery, the aim of the study was to examine muscle tissue response to implanted oxidized cellulose. MATERIAL AND METHODS: RESO-Cell® (Resorba Wundversorgung GmbH, Nuremberg, Germany) standard was implanted in the latissimus dorsi of 20 rats; subsequently, 12 samples were processed for histological evaluation after 4 and 8 weeks. The remaining 8 samples were processed for mRNA expression analyses of gene-encoding growth factors and collagens using quantitative reverse transcription polymerase chain reaction (RT-qPCR). RESULTS: Muscle tissue exposed to oxycellulose showed elevated mRNA levels of COL1A1 compared to untreated muscle tissue. The histological analysis revealed that no undegraded oxycellulose was detectable after as little as 4 weeks. Furthermore, a strong accumulation of CD68-positive foam cells was found in the treated area. CONCLUSIONS: In conclusion, the study has shown that oxidized cellulose can cause an inflammatory response after this material is implanted in skeletal muscle. Therefore, it is not recommended to leave this material in the body over a long period. However, it could be used as auxiliary material in the treatment of periodontal defects.

Histological comparison between laser microtome sections and ground specimens of implant-containing tissues.

Evaluation of bone regeneration and peri-implant bone apposition can only be accomplished using laboratory techniques that allow assessment of decalcified hard tissue. It is known that 5-15µm thick sections can be prepared with the cutting-grinding technique, but their production causes a high material loss (≥0.5mm) between two sections and requires years of training and experience. With the development of the laser microtome it has become possible to cut decalcified bone without high sample material loss. Many scientific publications deal with the application possibilities of the individual methods So far, there is no comparison work between the cutting-grinding technique and laser microtomy. For this reason, new tissue sections were prepared by laser microtome and analyzed histologically from samples that had been previously been prepared by the cutting-grinding technique. Using both methods, it could be demonstrated that the different implants were completely surrounded by a connective tissue layer. In sections (50-100µm) produced by the routine cutting-grinding technique, magnifications up to 20× revealed no detailed histological information because cell structures could not be clearly identified. By contrast, laser microtome sections (10µm) revealed these information as e.g. osteocytes are already clearly visible at 10× magnification. Furthermore, the interface between implant and the surrounding bone could be clearly demonstrated due to visible demarcation between a capsule and connective tissue. At the histological level, laser microtome sections were clearly superior at thicknesses ≥30µm compared to sections produced by the cutting-grinding technique. In addition, laser microtomy has the advantages of time saving and markedly reduced sample loss, especially in cases of the production of serial sections.

In vivo analysis of covering materials composed of biodegradable polymers enriched with flax fibers.

BACKGROUND: The objective of this study was to investigate the in vivo effect of bioactive composites with poly(lactic acid) (PLA) or polycaprolactone (PCL) as the matrix, reinforced with bioplastic flax fibers, on the surrounding muscle tissue. METHODS: Materials of pure PLA and PCL and their composites with flax fibers from genetically modified plants producing poly-3-hydroxybutyrate (PLA-transgen, PCL-transgen) and unmodified plants (PLA-wt, PCL-wt) were placed subcutaneous on the M. latissimus dorsi for four weeks. RESULTS: The analysis of histological samples revealed that every tested material was differently encapsulated and the capsule thickness is much more pronounced when using the PCL composites in comparison with the PLA composites. The encapsulation by connective tissue was significantly reduced around PCL-transgen and significantly increased in the cases of PLA-transgen and PLA-wt. In the collected muscle samples, the measured protein expression of CD45, lymphocyte common antigen, was significantly increased after the use of all tested materials, with the exception of pure PCL. In contrast, the protein expression of caveolin-1 remained unchanged after treatment with the most examined materials. Only after insertion of PLA-wt, a significant increase of caveolin-1 protein expression was detected, due to the improved neovascularization. CONCLUSION: These data support the presumption that the new bioactive composites are biocompatible and they could be applicable in the medical field to support the regenerative processes.

Radiographic Study of the Prevalence and Distribution of Hypodontia Associated with Unilateral and Bilateral Clef Lip and Palate in a Hungarian Population.

BACKGROUND Cleft defects are one of the most frequent birth-deformities of the orofacial region and they are commonly associated with anomalies of the tooth structure, size, shape, formation, eruption, and tooth number. The aim of our study was to evaluate the prevalence, distribution, and potential association of combined hypodontia in cleft-affected patients with regard to all types of teeth in both jaws in the permanent dentition. MATERIAL AND METHODS This retrospective radiographic analysis included patients with various types of clefts treated orthodontically in the Department of Orofacial Orthopedics and Orthodontics at Heim Pàl Children's Hospital, Budapest. There were 150 patients (84 males, 66 females) with non-syndromic unilateral (UCLP; n=120 patients) or bilateral (BCLP; n=30 patients) cleft formation (lip, alveolus and palate) who met the inclusion criteria. Statistical analysis was performed using the chi-square test and Fisher's exact test (significance level p<0.05). RESULTS Hypodontia was significantly more frequent in patients with cleft-sided lateral incisor (104 patients, 69%), with a total of 235 missing teeth, followed by the second premolars of the upper and lower jaw. A significant correlation of congenital missing teeth was observed in left-sided clefts between the upper and lower second premolar in the cleft area CONCLUSIONS Hypodontia inside and outside the cleft area was frequently observed. This should affect the therapy plans, especially if the cleft-sided premolar is also absent. Further comprehensive research including numerous random samples is necessary for better estimating other possible associations.

Bone Regeneration after Treatment with Covering Materials Composed of Flax Fibers and Biodegradable Plastics: A Histological Study in Rats.

The aim of this study was to examine the osteogenic potential of new flax covering materials. Bone defects were created on the skull of forty rats. Materials of pure PLA and PCL and their composites with flax fibers, genetically modified producing PHB (PLA-transgen, PCL-transgen) and unmodified (PLA-wt, PCL-wt), were inserted. The skulls were harvested after four weeks and subjected to histological examination. The percentage of bone regeneration by using PLA was less pronounced than after usage of pure PCL in comparison with controls. After treatment with PCL-transgen, a large amount of new formed bone could be found. In contrast, PCL-wt decreased significantly the bone regeneration, compared to the other tested groups. The bone covers made of pure PLA had substantially less influence on bone regeneration and the bone healing proceeded with a lot of connective tissue, whereas PLA-transgen and PLA-wt showed nearly comparable amount of new formed bone. Regarding the histological data, the hypothesis could be proposed that PCL and its composites have contributed to a higher quantity of the regenerated bone, compared to PLA. The histological studies showed comparable bone regeneration processes after treatment with tested covering materials, as well as in the untreated bone lesions.

Interrelationship between bone substitution materials and skeletal muscle tissue.

Bone density and quantity are primary conditions for the insertion and stability of dental implants. In cases of a lack of adequate maxillary or mandibulary bone, bone augmentation will be necessary. The use of synthetic bioactive bone substitution materials is of increasing importance as alternatives to autogenously bone grafts. It is well known that bone can influence muscle function and muscle function can influence bone structures. Muscles have a considerable potential of adaptation and muscle tissue surrounding an inserted implant or bone surrogate can integrate changes in mechanical load of the muscle and hereupon induce signaling cascades with protein synthesis and arrangement of the cytoskeleton. The Musculus latissimus dorsi is very often used for the analyses of the in vivo biocompatibility of newly designed biomaterials. Beside macroscopically and histologically examination, biocompatibility can be assessed by analyses of the biomaterial influence of gene expression. This review discusses changes in the fiber type distribution, myosin heavy chain isoform composition, histological appearance and vascularization of the skeletal muscle after implantation of bone substitution materials. Especially, the effects of bone surrogates should be described at the molecular-biological and cellular level.

Socket augmentation using a commercial collagen-based product--an animal study in pigs.

The aim of the present study was to identify properties of pure collagen for augmentation techniques and compare to a proved xenogenic material and natural bone regeneration. For that the osteogenesis of extraction alveoli after augmentation with a collagen cone covered with an absorbable collagen membrane in a single product (PARASORB Sombrero®, Resorba) was evaluated in a pig model. Extraction alveoli were treated with the collagen cone and the collagen membrane in a single product (test group; n=7) or demineralized bovine bone mineral and a collagen membrane (two separate products; positive control; n=7). Untreated alveoli were used (n=6) as negative controls.(1) Bone specimens were extracted 1 and 3 months after teeth extraction. Serial longitudinal sections were stained with Masson Goldner trichrome. Furthermore, bone specimens were examined using X-ray analyses. Significant differences of bone atrophy were detected 12 weeks after material insertion using X-ray analyses. The bone atrophy was reduced by approximately 32% after insertion of the positive control (P=0.046). Bone atrophy reached 37.6% of those from untreated alveoli (P=0.002) using the test group. After 4 weeks, bone formation was noticeable in most sites, whereas after 12 weeks of healing, specimens of all groups exhibited nearly complete osseous organization of the former defected area. The mandibulary bone texture showed typical spongious bone structures. Histomorphometric analyses revealed after 4 and 12 weeks significant higher levels of bone marrow in test and negative control than in positive control. Quantification of bone tissue and osteoid does not show any significant difference. The present study confirms reduced bone resorption following socket augmentation with an absorbable collagen membrane with collagen cone while the resulting bone structure is similar to natural bone regeneration. Pure collagen can be used for bone augmentation, and shows over other xenogenic materials, a clear advantage with respect to the bone density and structure.