Effect of chin-cup treatment on the temporomandibular joint: a systematic review

SummaryAim: To systematically search the literature and assess the available evidence for the influence of chin-cup therapy on the temporomandibular joint regarding morphological adaptations and appearance of temporomandibular disorders (TMD). Materials and methods: Electronic database searches of published and unpublished literature were performed. The following electronic databases with no language and publication date restrictions were searched: MEDLINE (via Ovid and PubMed), EMBASE (via Ovid), the Cochrane Oral Health Group's Trials Register, and CENTRAL. Unpublished literature was searched on ClinicalTrials.gov, the National Research Register, and Pro-Quest Dissertation Abstracts and Thesis database. The reference lists of all eligible studies were checked for additional studies. Two review authors performed data extraction independently and in duplicate using data collection forms. Disagreements were resolved by discussion or the involvement of an arbiter. Results: From the 209 articles identified, 55 papers were considered eligible for inclusion in the review. Following the full text reading stage, 12 studies qualified for the final review analysis. No randomized clinical trial was identified. Eight of the included studies were of prospective and four of retrospective design. All studies were assessed for their quality and graded eventually from low to medium level of evidence. Based on the reported evidence, chin-cup therapy affects the condylar growth pattern, even though two studies reported no significance changes in disc position and arthrosis configuration. Concerning the incidence of TMD, it can be concluded from the available evidence that chin-cup therapy constitutes no risk factor for TMD. Conclusion: Based on the available evidence, chin-cup therapy for Class III orthodontic anomaly seems to induce craniofacial adaptations. Nevertheless, there are insufficient or low-quality data in the orthodontic literature to allow the formulation of clear statements regarding the influence of chin-cup treatment on the temporomandibular join

Erratum: Determination of Dissociation Energies and Thermal Functions of Hydrogen Bond Formation Using High Resolution FTIR Spectroscopy [J. Chem. Phys. 8 7, 5674 (1987)]

Erratu

Determination of Dissociation Energies and Thermal Functions of Hydrogen‐bond Formation using High Resolution FTIR Spectroscopy

A technique which employs high resolution Fourier transform infrared spectroscopy is demonstrated for evaluation of hydrogen bonddissociation energiesD 0 and D e . Results for HCN‐‐HF give a D 0=20.77(22) and D e =28.77(45) kJ/mol which are compared with previously determined values obtained from microwave absolute intensity measurements and a b i n i t i o molecular orbital calculations. Rovibrational band information available for HCN‐‐HF also permits evaluation of thermal functions of dimer formation in kJ/mol: ΔU ○ 298.2 =20.1(2), ΔH ○ 298.2 =22.6(2), ΔG ○ 298.2 =59.4(2), ΔS ○ 298.2 =−0.1235

Knowledge of Postgraduate Dental Students on Evidence-based Dentistry and Research Methodology. An International Survey

PURPOSE To assess the knowledge of postgraduate dental students about evidence-based methodology pertaining to the design, conduct, and critical appraisal of clinical trials. MATERIALS AND METHODS Senior postgraduate students were surveyed from the dental schools of three universities in Athens (Greece), Boston (USA), and Zürich (Switzerland). The proportion of students correctly answering each of the 10 questions of the survey, as well as the cumulative scores, were analysed statistically with descriptive statistics and logistic/linear regression analysis at α = 5%. RESULTS A total of 96 students with a mean age of 30.0 years attained an overall correct score of 45.6% ± 15.0%, with correct answers to each question ranging from 13.5% to 86.5%. The questions most frequently answered incorrectly pertained to characterising sensitivity/specificity (13.5%), the number needed to treat (14.0%), the credibility of trial synthesis in meta-analysis (23.7%), and publication bias (29.5%). The vast majority of postgraduate students could correctly identify the role of statistical power of a trial (63.8%), random allocation sequence in a randomised trial (76.0%), and blinding in a randomised trial (86.5%). Paediatric dentistry postgraduate students scored better than students from other departments (+15.1%; 95% CI: 3.0% to 27.1%; p = 0.02). CONCLUSIONS Postgraduate students in orthodontics and other dental specialties possessed moderate knowledge on evidence-based methodology and clinical trials. Efforts should be made to integrate such subjects in university postgraduate curricula, so that future dental specialists can critically appraise such research papers

The Effect of Leveling the Curve of Spee on the Inclination of Mandibular Incisors: A Retrospective Cephalometric Study

PURPOSE To assess mandibular incisor inclination after leveling the curve of Spee (CoS) in patients treated with fixed appliances. MATERIALS AND METHODS This was a retrospective study, which included 80 consecutive patients with a mild CoS treated without extraction but with various biomechanical approaches. The depth of CoS was digitally measured on scanned plaster casts and mandibular incisor inclination was assessed with lateral cephalograms pre- and posttreatment. Patients were treated with 0.018"-slot edgewise fixed appliances and cinched back wires. Data were analyzed using linear regression modeling at 5%. RESULTS A total of 80 patients (40% female; mean age 13.8 years) were included with mean ANB = 4.4 ± 1.9°, mean SN/ML = 31.7 ± 4.7°, mean L1/ML = 95.0 ± 7.7°, and a mean depth of CoS = 1.1 ± 0.4 mm. The depth of CoS was leveled by -0.85 ± 0.39 mm to a post-treatment median of 0.18 mm (interquartile range = 0.09 to 0.35 mm). A small mandibular incisor proclination was observed through treatment (2.49 ± 9.1°), but this was not associated with the reduction in the depth of CoS (p > 0.05) and no statistically significant modifying effect from the different treatment mechanics was observed. CONCLUSION Under the limitations of this study, leveling a mild CoS was not associated with mandibular incisor proclination during fixed-appliance treatment

Heritability of facial soft tissue growth in mono- and dizygotic twins at 12 and 17 years of age: A retrospective cohort study

OBJECTIVE The purpose of this investigation of untreated monozygotic and dizygotic twins was to identify the genetic and environmental components to the facial soft tissue growth. SETTINGS AND SAMPLE POPULATION The sample consisted of 52 untreated monozygotic twins (36 male and 16 female) and 46 untreated dizygotic twins (23 male and 23 female) from the Forsyth Moorrees Twin Study (1959-1975). MATERIALS AND METHODS Lateral cephalograms were taken at 12 and 17 years of age and traced to analyse facial convexity, nasolabial angle, upper and lower lip thickness, upper and lower lip profile and nose prominence. The genetic and environmental components of variance were analysed with structural equation modelling for multilevel mixed-effects model. RESULTS At 12 years of age, strong additive genetic influence was seen for facial convexity (70%), upper lip profile (66%) and nose prominence (65%), whereas strong dominant genetic components were found for upper lip thickness (56%). Nevertheless, under unique environment influence were nasolabial angle (58%), lower lip profile (51%) and lower lip thickness (64%). At 17 years of age, only upper lip thickness (55%) and nose prominence (84%) were under strong additive genetic control, while the rest of the variables were under strong dominant genetic control. The only exception was lower lip thickness (61%), which is still influenced by the unique environment. CONCLUSION Although monozygotic/dizygotic twins share at least part of their genome, at both times either additive, dominant or environmental components were found. Nevertheless, at 17 years of age most of the variables are either under additive or dominant genetic influence

The \u3ci\u3eN\u3c/i\u3e-Acetyltransferase RimJ Responds to Environmental Stimuli to Repress \u3ci\u3epap\u3c/i\u3e Fimbrial Transcription in \u3ci\u3eEscherichia coli\u3c/i\u3e

In uropathogenic Escherichia coli, P pili (Pap) facilitate binding to host epithelial cells and subsequent colonization. Whereas P pili can be produced at 37°C, the expression of these fimbriae is suppressed at 23°C. Previously, insertion mutations in rimJ, a gene encoding the N-terminal acetyltransferase of ribosomal protein S5, were shown to disrupt this thermoregulatory response, allowing papBA transcription at low temperature. In this study, we created an in-frame deletion of rimJ. This deletion relieved the repressive effects not only of low temperature but also of rich (Luria-Bertani [LB]) medium and glucose on papBA transcription, indicating that RimJ modulates papBA transcription in response to multiple environmental stimuli. papI transcription was also shown to be regulated by RimJ. papBA transcription is also controlled by a phase variation mecha- nism. We demonstrated that the regulators necessary to establish a phase ON state—PapI, PapB, Dam, Lrp, and cyclic AMP-CAP–are still required for papBA transcription in a rimJ mutant strain. rimJ mutations increase the rate at which bacteria transition into the phase ON state, indicating that RimJ inhibits the phase OFF3ON transition. A rimJ hns651 mutant is viable on LB medium but not on minimal medium. This synthetic lethality, along with transcriptional analyses, indicates that RimJ and H-NS work through separate pathways to control papBA transcription. Mutations in rimJ do not greatly influence the transcription of the fan, daa, or fim operon, suggesting that RimJ may be a pap-specific regulator. Overexpression of rimJ under conditions repressive for papBA transcription complements the rimJ mutation but has little effect on tran- scription under activating conditions, indicating that the ability of RimJ to regulate transcription is environ- mentally controlled

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 programm

The time-dependent biomechanical behaviour of the periodontal ligament--an in vitro experimental study in minipig mandibular two-rooted premolars

The aim of the present work was to evaluate the biomechanical behaviour of the periodontal ligament (PDL) with respect to force development with different controlled loading velocities. For this purpose, an in vitro experimental study was performed on 18 minipig jaw segments. Displacements with variable increasing loading time were applied to one premolar crown of each jaw segment into the linguobuccal direction through a force sensor provided by a specialized biomechanical set-up. The predefined displacement values to be achieved were 0.1 and 0.2 mm. Each of the given displacement increments was applied on the specimens with a linear displacement increase employing the following time spans: 5, 10, 20, 30, 60, 120, 300, 450, and 600 seconds. Force values were measured during load application to register force/displacement diagrams and after the maximum displacement was reached force decay was monitored for a period of 600 seconds. Force/time curves for each tooth were plotted according to the data obtained. Diagrams of the maximum force values obtained from these plots and the force at the end of each measurement were extracted for all teeth. Forces at the point when maximum displacement was reached ranged from 0.5 to 2.5 N for the 0.1 mm activation and showed extreme variation with the specimens. The factor of volume and surface area of the individual roots were evaluated and found not to be responsible for these deviations. A comparable behaviour was recorded for the 0.2 mm deflection, however, on a higher force level. The results show that the force development at different displacement velocities is complex and dominated by the PDL biomechanical characteristics

Characterisation and microleakage of a new hydrophilic fissure sealant – UltraSeal XT® hydro™

Objectives: The new hydrophilic fissure sealant, UltraSeal XT® hydro™ (Ultradent Products, USA), was characterised and its in vitro resistance to microleakage after placement on conventionally acid etched and sequentially lased and acid etched molars was investigated. Materials and Methods: The sealant was characterised by Fourier transform infra-red spectroscopy, (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Vickers indentation test. Occlusal surfaces of extracted human molars were either conventionally acid etched (n = 10), or sequentially acid etched and laser irradiated (n = 10). UltraSeal XT® hydro™ was applied to both groups of teeth which were then subjected to 2500 thermocycles between 5 and 55 °C prior to microleakage assessment by fuchsin dye penetration. Results: UltraSeal XT® hydro™ is an acrylate-based sealant which achieved a degree of conversion of 50.6 ± 2.2% and a Vickers microhardness of 24.2 ± 1.5 under standard light curing (1000 mWcm-2 for 20 s). Fluoride ion release was negligible within a 14-day period. SEM and EDX analyses indicated that the sealant comprises irregular sub-micron and nano-sized silicon-, barium- and aluminium-bearing filler phases embedded within a ductile matrix. Laser preconditioning was found to significantly reduce microleakage (Mann-Whitney U test, p < 0.001). The lased teeth presented enhanced surface roughness on a 50 to 100 μm scale which caused the segregation and concentration of the filler particles at the enamel-sealant interface. Conclusion: Laser preconditioning significantly decreased microleakage and increased enamel surface roughness which caused zoning of the filler particles at the enamel-sealant interface