The Erasmus programme for postgraduate education in orthodontics in Europe: an update of the guidelines.

In 1989, the ERASMUS Bureau of the European Cultural Foundation of the Commission of the European Communities funded the development of a new 3-year curriculum for postgraduate education in orthodontics. The new curriculum was created by directors for orthodontic education representing 15 European countries. The curriculum entitled 'Three years Postgraduate Programme in Orthodontics: the Final Report of the Erasmus Project' was published 1992. In 2012, the 'Network of Erasmus Based European Orthodontic Programmes' developed and approved an updated version of the guidelines. The core programme consists of eight sections: general biological and medical subjects; basic orthodontic subjects; general orthodontic subjects; orthodontic techniques; interdisciplinary subjects; management of health and safety; practice management, administration, and ethics; extramural educational activities. The programme goals and objectives are described and the competencies to be reached are outlined. These guidelines may serve as a baseline for programme development and quality assessment for postgraduate programme directors, national associations, and governmental bodies and could assist future residents when selecting a postgraduate programme.

Three-dimensional analysis of initial biofilm formation on polytetrafluoroethylene in the oral cavity.

AIM: There is published evidence that polytetrafluoroethylene (PTFE) exhibits beneficial surface characteristics by means of long-term biofilm accumulation. The purpose of this study was to investigate and compare early biofilm formation on polytetrafluoroethylene, ceramic-reinforced polytetrafluoroethylene and as the control group, stainless steel. MATERIALS AND METHODS: This study comprised 10 healthy volunteers (5 females and 5 males) with a mean age of 27.3 ± 3.7 years. Three different slabs (two PTFE coatings: one pure and one ceramic-reinforced polytetrafluoroethylene, and stainless steel) were placed in random order on a splint in the mandibular molar region. Intraoral splints were inserted for 48 h. After 48 h, we removed the slabs from the splints and stained the biofilm with a two-color fluorescence assay for bacterial viability (LIVE/DEAD BacLight-Bacterial Viability Kit 7012, Invitrogen, Mount Waverley, Australia). The amount of biofilm accumulation was assessed using confocal laser scanning microscopy (CLSM). RESULTS: The biofilm surface coverage was 55.8 ± 39.8% on pure PTFE-coated probes, 55.9 ± 35.0% on ceramic-reinforced PTFE-coated probes, and 33.3 ± 37.8% on stainless steel. The differences among the three groups were not significant (p = 0.301). Biofilm depth was 5.6 ± 5.4 µm on pure PTFE-coated probes, 5.2 ± 3.8 µm on ceramic-reinforced PTFE-coated probes, and 2.4 ± 2.9 µm on stainless steel. The Friedman test revealed a significant difference in biofilm depth (p = 0.002). Pairwise comparison of biofilm accumulation yielded a significant difference between pure PTFE and ceramic-reinforced PTFE compared to stainless steel (p = 0.017; p = 0.005). CONCLUSION: Our results indicate that the beneficial surface characteristics of PTFE coatings by reducing long-term biofilm are not a result of inhibiting initial bacterial adhesion.

Stress analysis of an all-ceramic FDP loaded according to different occlusal concepts.

The aim of this study was to investigate the influence of four different occlusal concepts on stress distribution in a four-unit fixed dental prosthesis (FDP) made of zirconia. A three-dimensional finite element (FE) model was created and four model versions with between 15 and 42 contact points were developed. A force of 300 N was distributed over the chewing surface according to the different occlusal concepts and virtually applied perpendicularly to the occlusal plane in each version. Then, FE analysis was performed and stress distribution evaluated. Generally, highest tensile stresses were located at the point of load application within the veneering layer and ranged from 104 to 204 MPa. The highest tensile stresses within the framework were located at the basal side of the connectors and ranged between 12 and 39 MPa. This study shows that the distribution of occlusal contact points significantly influences the stresses induced by occlusal forces in four-unit all-ceramic fixed dental prostheses and strongly suggests that the number and distribution of occlusal contacts may be important to minimise fatigue effects caused by cycling.

Caries outcomes after orthodontic treatment with fixed appliances: do lingual brackets make a difference?

Orthodontic treatment with fixed appliances is considered a risk factor for the development of white spot caries lesions (WSL). Traditionally, brackets are bonded to the buccal surfaces. Lingual brackets are developing rapidly and have become more readily available. Buccal surfaces are considered to be more caries prone than lingual surfaces. Furthermore, lingual brackets are shaped to fit the morphology of the teeth and seal almost the entire surface. In the present study we tested the hypothesis that lingual brackets result in a lower caries incidence than buccal brackets. We tested this hypothesis using a split-mouth design where subjects were allocated randomly to a group receiving either buccal or lingual brackets on the maxillary teeth and the alternative bracket type in the mandible. The results indicate that buccal surfaces are more prone to WSL development, especially when WSL existed before treatment. The number of WSL that developed or progressed on buccal surfaces was 4.8 times higher than the number of WSL that developed or progressed on lingual surfaces. When measured using quantitative light-induced fluorescence (QLF), the increase in integrated fluorescence loss was 10.6 times higher buccally than lingually. We conclude that lingual brackets make a difference when caries lesion incidence is concerned.

Reduction of biofilm on orthodontic brackets with the use of a polytetrafluoroethylene coating.

SUMMARY: Treatment with fixed orthodontic appliances can cause enamel demineralization by increased biofilm adhesion. The purpose of the present study was to investigate whether a polytetrafluoroethylene (PTFE) coating reduces biofilm formation on orthodontic brackets. One PTFE-coated bracket and one uncoated stainless steel bracket were bonded symmetrically on the first or second (four maxillary and nine mandibular) primary molars in 13 adolescent patients (five females and eight males, aged 11.2 +/- 2.8 years; four dropouts) for 8 weeks. Quantitative biofilm formation on brackets was analysed with the Rutherford backscattering detection (RBSD) method, a scanning electron microscopy technique. A total of five RBSD micrographs were obtained per bracket with views from the buccal, mesial, distal, cervical, and occlusal aspects. A two-sided paired t-test was used to compare data. A P-value less than 0.05 was considered significant. Total biofilm formation was 4.0 +/- 3.6 per cent of the surface on the PTFE-coated brackets and 22.2 +/- 5.4 per cent on uncoated brackets. Differences between the two groups were statistically significant (P < 0.05). Pairwise comparison of biofilm formation with respect to location (buccal, mesial, distal, cervical, and occlusal) revealed a significantly lower biofilm accumulation on PTFE-coated brackets on all surfaces. The results indicate that PTFE coating of brackets reduces biofilm adhesion to a minimum and might have the potential to reduce iatrogenic side effects, e.g. decalcification during orthodontic treatment with fixed appliances.

Short-term influence of lingual orthodontic therapy on microbial parameters and periodontal status. A preliminary study.

OBJECTIVE: To perform a preliminary study of the short-term effect of fixed, customized lingual orthodontic appliances on periodontal and microbial parameters. MATERIALS AND METHODS: The sample comprised 20 subjects (6 males and 14 females) with a mean age of 22.3 years +/- 8.6 years. Before (T(0)) and 4 weeks after placement (T(1)) of custom-made lingual appliances on the lower teeth only, plaque index (PI), probing pocket depth (PPD), and bleeding on probing (BOP) were measured. A 16S rRNA-based polymerase chain reaction (PCR) method was used to detect Aggregatibacter actinomycetemcomitans ( Aa ) and Porphyromonas gingivalis ( Pg ) in the crevicular fluid. To compare periodontal parameters on bonded lingual (testing) and unbonded palatal (control) and labial (control) sites between T(0) and T(1), the Wilcoxon test was applied. RESULTS: On the lingual aspects of bonded teeth, a significant increase of BOP (T(0): 23.4 +/- 22.5%; T(1): 46.2 +/- 23.5%; P = .001) and PI (T(0): 0.3 +/- 0.3; T(1): 1.0 +/- 0.7; P = .001) was observed, but no significant changes for PPD (T(0): 2.1 +/- 0.4 mm; T(1): 2.2 +/- 0.3 mm; P = .286) were found. On control sites, no significant changes were recorded for any periodontal parameter. Aa was found in 25% of the patients at baseline (5 subjects) and in 35% of the patients at T(1) (2 additional positive subjects), whereas Pg was found in 5% of the cohort at T(0) and at T(1) (same patient). CONCLUSIONS: Even in the short term, insertion of fixed lingual appliances induced a worsening of periodontal parameters restricted to bonded lingual sites.

Influence of lingual orthodontic therapy on microbial parameters and periodontal status in adults.

Insertion of fixed orthodontic appliances can induce an increase in oral biofilm and thereby cause inflammation of the periodontal tissues. The purpose of this study was to perform a longitudinal analysis of clinical and microbial parameters after insertion of lingual brackets. Bleeding on probing (BOP), plaque index (PI), and pocket probing depth (PPD) were measured in 10 adults (8 females and 2 males, aged 29.0 +/- 4.7 years) who received treatment with custom-made lingual appliances (Incognito/iBraces) before (T0) and 3 months after beginning of treatment (T1). No supportive dental prophylaxis was undertaken. In addition, a 16S rRNA-based polymerase chain reaction (PCR) method was used to detect Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) in the crevicular fluid. A Wilcoxon test was used to compare clinical parameters at the buccal (control) and lingual sites between T0 and T1. At T0, BOP was 12.4 +/- 8.2 per cent, PPD 2.1 +/- 0.3 mm, and PI 0.1 +/- 0.2 at the buccal sites and at T1 14.3 +/- 8.1 per cent, 2.1 +/- 0.2 mm and 0.1 +/- 0.2, respectively. At the lingual sites, BOP was 22.2 +/- 19.0 per cent, PPD 2.3 +/- 0.3 mm, and PI 0.1 +/- 0.2 at T0 and at T1 56.2 +/- 31.6 per cent, 2.9 +/- 0.3 mm, and 1.2 +/- 1.1, respectively. Differences between T0 and T1 were significant for clinical parameters only at the lingual sites. Aa was found in five patients at baseline and in four at T1, whereas Pg was found in one patient at T0 and in two at T1. Insertion of fixed lingual appliances without supportive dental prophylaxis induced a worsening of clinical parameters restricted to the lingual sites, whereas the relative prevalence of Aa and Pg remained unchanged.

Analysis of supra- and subgingival long-term biofilm formation on orthodontic bands.

Insertion of fixed orthodontic appliances induces increased biofilm formation caused by a higher number of plaque-retentive sites. The purpose of the study was to perform a quantitative analysis of supra- and subgingival long-term biofilm formation on orthodontic bands. Ten patients (five females and five males, aged 18.3+/-5.4 years) who had received therapy with fixed orthodontic appliances for 24+/-9 months were enrolled in the study. Biofilm formation on 28 orthodontic bands was analyzed quantitatively with the Rutherford backscattering detection method, a scanning electron microscopy technique. The biofilm formation for the supra- and subgingival surfaces was calculated from the grey values. Statistical analysis was performed with a mixed model with the patient as the random factor. A P-value <0.05 was considered significant. A biofilm was found on 16.1+/-9.2 per cent of supragingival surfaces and on 3.6+/-4.4 per cent of subgingival surfaces. Differences in biofilm formation in supra- and subgingival surfaces were statistically significant (P<0.05) and formed a distinct demarcation line. Despite the presence of supragingival biofilm, no mature subgingival biofilm was found on the tested orthodontic bands.

Dental implants in patients with orofacial clefts: a long-term follow-up study.

Aim of this study was to determine the success of implants that were inserted in patients with cleft of the lip, alveolus and palate (CLAP) and to identify prognosis-relevant factors. In a prospective evaluation, 75 implants inserted in combination with bone grafting at cleft sites of 45 patients were examined. The observation period extended 5.5 years in average (minimum 1.5, maximum 11.3 years). Implant success was evaluated clinically and radiographically and was compared to age- and gender-matched control groups. Statistic assessment included Kaplan-Meier survival analysis, Log rank tests and Cox regression analysis. In total, 10 implants were lost in 8 patients, resulting in an implant survival rate of 82.2% at the end of the observation period. Patient-related parameters of age, gender or type of cleft had no significant influence. The length of an implant was significantly related to an improved survival rate (P<0.01). Implant survival was less in CLAP patients when compared to implant insertions in a non-cleft control group, but improved when compared to patients with bone grafting for other indications. It is concluded that implants combined with bone grafting can offer a reliable alternative in patients with CLAP.

Autotransplantation of immature third molars into edentulous and atrophied jaw sections.

The aim of the present study was to assess the results after transplantation of 85 immature third molars. Recipient site conditions varied and different surgical techniques were used. The long-term results after preparation of a new alveolus, splitting osteotomy of the alveolar process or use of free bone autografts were compared with the results after transplantation into a fresh extraction site (control group). Transplantations into prepared sockets showed equal results to the control group (94% respectively). Transplantations in connection with free bone autografts (84%) or after splitting osteotomy of the alveolar process (63%) showed poorer success rates, the differences between the latter and the control group being statistically significant. A possible correlation to revascularization disturbances of the pulp due to an insufficiency of the recipient site or to postoperative infection is suspected. The results show that transplantation of immature third molars is a safe, useful procedure when appropriate conditions of the recipient site are present. Where the alveolus is atrophic, a splitting osteotomy should be performed only in exceptional cases and preference should be given to alternative methods such as primary bone augmentation or bone-regenerative procedures.

The learning unit "Orthodontic set-up" as a new-media module in teaching.

The present study examines the extent to which computer-assisted learning units provided independently of place and time are used in self-study as a supplement to the classical classroom instruction of dental students. Indications as to whether such teaching modules improve training in orthodontics should be obtained from this. Attention was focussed on the implementation and evaluation of the "Orthodontic set-up" teaching module, which can be accessed in the Internet and Intranet of the university. The didactic arrangement offered classical university courses in parallel (four lectures on the subjects of occlusion, function, diagnostics, and therapy) in addition to the electronically communicated teaching contents. In addition, intensive supervision during the production of the set-up was guaranteed. The use of this multimedia learning concept was in general assessed positively by 63 surveyed students in the 2002/03 winter semester. The results revealed on the one hand the intensity of use and features of the acquisition of knowledge (use types), and on the other hand, in terms of professional relevance, the contents were found to be well explained, didactically attractive, and understandably presented. However, numerous drawbacks were also mentioned (technical and time problems; qualification deficits). The experience gained in this project should encourage more future investment in the development of alternative university didactic models.

Functional improvement of the mandibular neuromuscular guidance by orthodontic-surgical treatment.

The primary aim of the study was to reveal whether adult patients with skeletal mandibular retrognathism combined with a dental Class II relationship without craniomandibular pain show a characteristic pattern of free mandibular movements compared to patients with a Class I skeletal and dental morphology. The secondary aim was to investigate whether these characteristic structures are subject to change following combined orthodontic-surgical treatment. Free mandibular movements were measured with an ultrasound device and analyzed with computer software developed by the authors. In all patients examined, 2 maxillarily and mandibularly fixed axes were found. These axes have no direct relation to the temporomandibular joints, are positioned above and anterior to the joints and maintain a constant distance. This gear system is referred to as a neuromuscularly determined dimeric link chain. The position of the mandible is defined by the rotational angle mu and the inclination angle alpha around the axes of the dimeric link chain. This dimeric link chain of free movements of patients with Class I skeletal and dental relationship functions according to the principle of least action: The angular velocities around the 2 axes show a constant ratio within the different segments of motion, and in the mu-alpha diagrams the segments of mandibular movements are represented by straight lines, the shortest paths between 2 positions. Individual cases and statistical data show that the structure of mandibular movements of patients with skeletal mandibular retrognathism combines with a dental Class II relationship without craniomadibular pain differs significantly from that of patients with Class I alignment. Mandibular retrognathism and a Class II relationship are accompanied by marked coordination disturbances in the rotary movements around the maxillary and mandibular neuromuscular axes. Following orthodontic-surgical treatment to restore ideal alignment of the occlusal, articular, and skeletal structures, the patients showed a similar pattern in the structure of mandibular movements to that of patients with Class I sketal and dental relationships. Thus, combined orthodontic-surgical treatment leads to measurable functional hamonization not only of the skeletal and dental structures but also of the neuromuscular guidance system.

Introduction of "vario plates" for retention after mandibular distraction osteogenesis.

This report introduces a new removable orthodontic appliance called "vario plates" for retention following distraction osteogenesis of the mandible. The "vario plates" consist of removable orthodontic appliances in the maxilla and the mandible. These are fabricated out of self-curing resin with typical wire elements. They are connected with telescoping maxillomandibular guidance rods, which have a smoothly variable length, from the maxillary molar region to the mandibular premolar region on each side. The telescope on both sides is adjustable in this length by means of a protrusion nut. Thus, it is possible to move the mandible forward an exactly controlled amount. The "vario plates" are in function for 24 hours a day in the patient for the first 6 months after mandibular distraction osteogenesis and subsequently only at night. The application of the plates is demonstrated in a patient with Goldenhar syndrome. Application of "vario plates" after distraction osteogenesis makes it possible to hold the mandible in a stable position. The combination of maxillofacial surgery with distraction osteogenesis and orthodontic treatment and retention leads to an improvement in therapy of patients with severe dentofacial anomalies.

Harmonization of free mandibular movements by orthodontic-surgical treatment of patients with mandibular retrognathism.

The aim of the following study was to investigate whether adult patients with mandibular retrognathism combined with a dental Class II relationship without craniomandibular pain show a characteristic structure of free mandibular movements caused by the neuromuscular system compared to patients with neutral skeletal and dental relationships. The authors also analyzed whether these characteristic structures changed following orthodontic-surgical treatment. To record the spatial movement of the mandible, an ultrasound measurement system was chosen and diagnostic software was developed for computer analysis of the recorded movements based on physical and biomechanical concepts. Clinically complaint-free, adult patients with mandibular retrognathism and distal bite exhibited a structure of mandibular movement that was markedly displaced as compared to patients with neutral skeletal and dental alignment. After completion of orthodontic and surgical treatment, it is apparent that the entire neuromuscular system of movement was transformed from one characterized by massive dysco-ordination to one of harmonized, coordinated motion, as is seen in patients with nonpathologic, neutral relation.

[Results of the application of the Goettingen concept for three-dimensional repositioning of the maxilla in orthognathic surgery]. / Ergebnisse der Anwendung des Göttinger Konzepts zur räumlichen Einstellung des Oberkiefers nach Umstellungsosteotomien.

During orthodontic-surgical treatment, a three-dimensional repositioning of the maxilla is needed after Le Fort I osteotomy. The preoperatively planned and desired position of the maxilla could often not be implemented satisfactorily in the surgical procedure. Several authors described deviations of up to 15 mm in the vertical dimension and 5 mm in the sagittal dimension between the planned and the achieved position. In order to avoid this error, the "model-repositioning instrument" for three-dimensionally controlled cast surgery and the "three-dimensional doublesplint method" in combination with a surgical facebow for actual surgery were developed. A group of 20 adult patients with severe dentofacial deformities were treated according to the Goettingen concept for combined orthodontic-surgical treatment with condylar position control with a surgical facebow. For each patient the position of three marked reference points on the maxillary dental arch under pre- and postoperative conditions was evaluated using superimposed tracings of lateral radiographs. These values were compared with the performed movements of the dental maxillary arch during cast surgery. It can be shown that with the new developments the planned position of the maxillary dental arch could be transferred from cast surgery to actual surgery with an accuracy of +/- 1 mm vertically and sagittally.

Functional conditions of the mandible: theory and physiology.

The functional conditions of the mandible are differentiated according to the number of kinematic degrees of freedom assigned to each mandibular movement. One degree of freedom: pro- and retrusive occlusal border movement. The interplay of the TMJs with the occluding teeth determines a compulsory course which corresponds to a 4-bar-chain guidance. 2 degrees of freedom: free sagittal mouth movement without tooth contact. Using graphic recordings of cyclic mandibular movements, the mobile hinge axis is identified as a mandibularly fixed line which is not directly categorized as a part of an anatomical structure. In the maxillary coordinate system, its movement describes a cylinder; sagittally, it describes a circle. The mandibular positions are clearly identifiable with 2 angles. The in vivo measurements show that neuromuscularly healthy systems supply the mandible with anticipatory guidance. 3 degrees of freedom: bolus function. The articular space in the TMJ is utilized.

Masticatory musculature under altered occlusal relationships--a model study with experimental animals.

In a study with experimental animals, the occlusal relationships of male Wistar rats were altered by the bilateral extraction of lateral teeth; the bolus function was eliminated by feeding a soft diet. Both steps led to relief of strain on the temporomandibular joint and thus also in the muscular system itself. The masticatory muscles adapted to the new experimental conditions. We observed a reduction in muscle dry weight and a shift in muscle fiber composition in favour of the IIb fibers, which indicates that less masticatory strength was required. Adaptation thus occurred equally on the macroscopic and microscopic levels.

Functional condition of the mandible: physical structures of free mandibular movement.

Starting with the physical definition of the concept "mobile hinge axis", which only allows 2 degrees of freedom for planar mandibular movement, it will be shown that the hinge axis of the temporomandibular joint cannot be found with a small mouth-opening rotation, as is usual but erroneous. By recording cyclic mandibular movements with a measuring system which itself possesses 6 degrees of freedom, the mobile hinge axis can be found. However, there are patients which do not use a mobile hinge axis, which is indicative of latent functional disturbances of the neuromuscular system.

Alteration of the functional condition of the mandible during clinical treatment.

Free mandibular movements and their neuromuscular guidance were measured with an ultrasonic device and analyzed with computer software developed by the authors. In all patients examined, we found maxillarly- and mandibularly-fixed axes which maintain a constant distance. This guidance system is named a neuromuscularly-determined dimeric link chain. The position of the mandible is defined by the 2 rotational angles (mu, alpha) around the axes of the dimeric link chain. This dimeric link chain of free movements normally functions according to the principle of least action. The angular velocities around the 2 axes show a constant ratio during the different segments of motion. In the mu-alpha-diagrams, the segments of movements of the mandible are represented by straight lines, the shortest path between 2 positions. Individual cases and statistical data show that the structure of mandibular movements of patients with skeletal mandibular retrognathism combined with dental class-II-relationship without craniomandibular pain significantly differs from the structure in patients with neutral alignment. Mandibular retrognathism and class-II-relationship are accompanied by marked coordination disturbances of rotations around the maxillary and mandibular neuromuscular axes. Following orthodontic-surgical treatment that restored ideal alignment of the occlusal, articular, and skeletal structures, the patients examined showed a similar pattern in the structure of mandibular movements to that of patients with neutral skeletal and dental relationships. Thus, combined orthodontic-surgical treatment leads to measurable functional harmonization not only of the skeletal and dental structures, but also of the neuromuscular guidance system.

Techniques for achieving three-dimensional positioning of the maxilla applied in conjunction with the Göttingen concept.

Three-dimensional repositioning of the maxilla is possible after Le Fort I osteotomy. However, the preoperatively planned and desired position of the maxillary dental arch often cannot be sufficiently achieved during actual surgery, and deviations in the sagittal and vertical dimensions are common. To reduce these errors, the model-repositioning instrument was developed for model surgery in conjunction with the Göttingen concept for orthodontic-surgical treatment with condylar position control. This instrument allows a controlled three-dimensional positioning of jaw segments with three reference points directly on the teeth. The three-dimensional double-splint method combined with a surgical facebow was developed for a controlled three-dimensional positioning of the maxilla during surgery. This instrument and method were applied during treatment of 20 adult patients, and the position of the maxilla before and after surgery was analyzed. It was found that the planned position of the maxillary dental arch could be transferred from model surgery to actual surgery with an accuracy of +/- 1 mm sagittally and vertically. Thus, the application of the Göttingen concept for three-dimensional positioning of the maxilla results in an improvement of accuracy compared with other methods. Furthermore, use of these procedures is easier and less time-consuming during model and actual surgery than are other procedures.