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Summary Objectives Interproximal enamel reduction (IPR) is routinely used in orthodontics to generate small to moderate amounts of space within the dental arch. Aim of this ex vivo study was to evaluate the effect of two different IPR systems on the enamel surface’s waviness, roughness, and elemental composition after 6 months of intraoral exposure. Materials and methods Fifteen orthodontic extraction patients were included in the present study. The 39 healthy premolars, which were scheduled to be extracted, were subjected to IPR at least 6 months before their extraction. IPR was performed on their mesial side with two different methods: (1) instrumented method with the Ortho-Strips system (on handpiece) and (2) manually with the Intensiv ProxoStrip (strips)—each with four different grits for contouring, finishing, and polishing. The distal side of each premolar served as its own internal control. Treated and untreated tooth surfaces were evaluated by optical profilometry, Raman, and scanning electron microscope/X-ray energy-dispersive (EDX) analyses. Data were analysed with descriptive statistics and generalized linear models at alpha = 5%. Results Both IPR methods significantly reduced the waviness of the enamel surface (P Conclusions Both stripping systems led to a flatter but rougher enamel surface. Further polishing is needed to restore the initial enamel smoothness. The elemental composition of the stripped enamel returns to the baseline level after 6 months of intraoral exposure.

Summary Background Orthodontic patients wearing fixed appliances are susceptible to traumatic dental injuries during contact-sport. This laboratory study investigated the protective qualities of orthodontic mouthguards using impact-testing to a typodont fitted with a fixed appliance through peak load transfer and retention of the mouthguard. Methods Seven orthodontic mouthguards [three custom-made (Medium-CM, Heavy-CM, Heavy-pro-CM); three commercially-available mouth-formed (Shock-Doctor® Ultra Braces, Opro® Ortho-Gold Braces, Opro® Ortho-Bronze Braces) and a Shock-Doctor® Instant-Fit] were fitted to a maxillary arch typodont bonded with a fixed appliance and impact-tested using 0.5 or 1 Joule (J) energy via hockey-ball, cricket-ball or steel-ball projectile. A load-cell recorded peak load transfer through mouthguard to typodont with retention scored in a binary manner dependent upon any displacement following impact. Differences across mouthguards were calculated with ANOVA or Kruskal–Wallis test for normal and non-normal data, respectively. Post hoc comparisons across mouthguards were conducted via Dunnett's test with Sidak correction. Results Only the three custom-made and Opro® Ortho-Gold Braces were not displaced by impact-testing. For these, Opro® Ortho-Gold Braces transferred the smallest load for 3/6 impact-tests, followed by Medium-CM. Heavy-pro-CM performed poorly, ranking penultimate or worst for all impact-tests. Significant differences were found between mouthguards for cricket-ball and steel-ball set-ups. The Opro® Ortho-Gold Braces performed better than the Heavy and Heavy-pro-CM for 0.5 J cricket-ball impact-test (P < 0.05), whilst Medium-CM performed better than Heavy-pro-CM. For 1 J cricket-ball, there were significant differences between Medium-CM and Heavy-pro-CM (P < 0.05). For 0.5 J steel-ball, the Medium-CM performed significantly better than both Heavy-pro-CM and Opro® Ortho-Gold Braces (P < 0.05), whilst Heavy-CM performed better than the Heavy-pro-CM (P < 0.05). For the 1 J steel-ball, Medium and Heavy-CM performed better than Opro® Ortho-Gold Braces (P < 0.05). Conclusions Opro® Ortho-Gold and Medium-CM mouthguards offer the best protection for low-impact sports, whilst Medium or Heavy-CM mouthguards are recommended for high-impact sport.

Summary Objective To investigate alterations in the mechanical properties of in-house three-dimensional (3D) printed orthodontic aligners after intraoral ageing. Materials and methods Sixteen 3D-printed aligners (TC-85DAC resin, Graphy, Seoul, Korea) were used for the purpose of the study, which were divided into 10 control (not used) aligners and 6 materials retrieved from 4 patients after 1-week service (retrieved group). Samples from the control group were analysed by attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) spectroscopy. Samples from control/retrieved groups were embedded resin and subjected to instrumented indentation testing (IIT) to record force–indentation depth curves, calculating the following (as per ISO 14577-1, 2002 standard): Martens hardness (HM), indentation modulus (EIT), and elastic index (ηIT), and the indentation relaxation index (RIT). Differences between control and retrieved 3D-printed aligners were checked with Mann–Whitney/t-tests at an alpha = 5%. Results ATR-FTIR analysis showed that aligners were made of a vinyl ester–urethane material. The results of the IIT testing were: HM (control: median 91.5 N/mm2, interquartile range [IQR] 88.0–93.0/as-retrieved: median 90.5 N/mm2, IQR 89.0–93.0); EIT (control, mean 2616.3 MPa, standard deviation [SD] 107.0 MPa/retrieved, mean 2673.2 MPa, SD 149.4 MPa); ηIT (control: median 28.6%, IQR 28.2–30.9%/as-retrieved: median 29.0%, IQR 28.7–29.2%); and RIT (control: median 45.5%, IQR 43.0–47.0%/as-retrieved: median 45.1%, IQR 45.0–45.3%). No differences between as-retrieved and control aligners were found for any of the mechanical properties tested (P > 0.05 in all instances). Conclusion The mechanical properties of the in-house 3D-printed aligners tested were not affected after 1 week in service period.

Summary Objective To assess three rapid maxillary expansion (RME) appliances in nasal ventilation. Trial design Three-arm parallel randomized clinical trial. Methods Sixty-six growing subjects (10–16 years old) needing RME as part of their orthodontic treatment were randomly allocated (1:1:1 ratio) to three groups of 22 patients receiving Hyrax (H), Hybrid-Hyrax (HH), or Keles keyless expander (K). The primary outcome of nasal ventilation (pressure and velocity) and secondary outcomes (skeletal, dental, soft tissue, and nasal obstruction changes) were blindly assessed on the initial (T0) and final (T1, 6 months at appliance removal) cone-beam computed tomography (CBCT) data by applying computational fluid dynamics (CFD) method. Differences across groups were assessed with crude and adjusted for baseline values and confounders (gender, age, skeletal maturation, expansion amount, mucosal/adenoid hypertrophy, nasal septum deviation) regression models with alpha = 5%. Results Fifty-four patients were analysed (19H, 21HH, 14K). RME reduced both nasal pressure (H: −45.8%, HH: −75.5%, K: −63.2%) and velocity (H: −30%, HH: −58.5%, K: −35%) accompanied with nasal obstruction resolution (H: 26%, HH: 62%, K: 50%). Regressions accounting for baseline severity indicated HH expander performing better in terms of post-expansion maximum velocity (P = 0.03) and nasal obstruction resolution (P = 0.04), which was robust to confounders. Mucosal/adenoid hypertrophy and nasal septum deviation changes were variable, minimal, and similar across groups. The HH resulted in significantly greater increase in the nasal cross-sectional area (62.3%), anterior (14.6%), and posterior (10.5%) nasal widths. Nasal obstruction resolution was more probable among younger (P = 0.04), skeletally immature (P = 0.03), and male patients (P = 0.02) without pre-treatment mucosal hypertrophy (P = 0.04), while HH was associated with marginal greater probability for obstruction resolution. Conclusions RME resulted in improvement of nasal skeletal parameters and simulated ventilation with the former being in favour of the HH and the latter not showing significant differences among the three appliances. Limitation Attrition in the K group due to blocked activation rods possibly leading to limited sample to identify any existing group differences. Harms Replacement of blocked Keles expanders for finalizing treatment. Protocol The protocol was not published before the trial commencement. Registration Australian and New Zealand Clinical Trial Registry; ACTRN12617001136392.

Summary Introduction This prospective clinical cohort study investigated the potential influence of obesity on orthodontic treatment outcome. Methods A prospective cohort of adolescent patients undergoing routine fixed appliance treatment were recruited into normal-weight or obese groups based upon body mass index (BMI) centile and followed up until the completion of treatment. Primary outcome was treatment duration, and secondary outcomes included treatment outcome (occlusal change measured using peer assessment rating [PAR]), appointment characteristics, and compliance measures. Results A total of 45 patients mean age 14.8 (1.6) years were included in the final analysis. The normal-weight group included 23 patients with mean BMI 19.4 (2.4) kg/m2 and the obese group 22 patients with mean BMI 30.5 (3.8) kg/m2. There were no significant differences in baseline demographics between groups, except for BMI and pre-treatment PAR. The normal-weight group had a mean pre-treatment PAR of 25.6 (8.3) and the obese 33.3 (11.8) giving the obese group a more severe pre-treatment malocclusion (P = 0.02). There were no significant differences in treatment duration between groups (P = 0.36), but obese patients needed less time per each additional baseline PAR point compared to normal weight (P = 0.02). Obese patients also needed less appointments compared to normal-weight patients (P = 0.02). There were no significant differences between groups for appointment characteristics or compliance. Finally, obese patients were more likely to experience a great PAR reduction than normal-weight patients (relative risk = 2.6; 95% confidence interval = 1.2–4.2; P = 0.02). Conclusions There were no significant differences in treatment duration between obese and normal-weight patients. Obesity does not appear to be a risk factor for negative orthodontic treatment outcome with fixed appliances.

Introduction His bundle pacing (HBP) aims to deliver physiological activation of the ventricles via the native His-Purkinje conduction system. A challenge of HBP is the limited market of implantation tools, pacing leads and specifically designed pacing algorithms. Purpose Over the last three years both Medtronic (MDT) and Boston Scientific (BSC) generators have been used for HBP in a large tertiary centre. We examined whether there was any difference between lead parameters and battery longevity depending on the type of manufacturer used. Methods Patients implanted with a MDT Select Secure model 3830 lead were included in this retrospective study. Data collected included HBP thresholds (analysed at 1ms pulse width) at implant and at the most recent device check, HBP percentages and battery longevity (months). Battery longevity were calculated by adding duration of follow up and estimated battery life at last follow up. Results A total of 31 patients were included for data analysis (58% male and mean age 72 years). 18 patients had MDT generators of which 3 were PPMs, 5 were CRT-Ps and 10 were CRT-Ds. 13 patients had BSC generators of which 5 were PPMs, 5 were CRT-Ps and 3 were CRT-Ds. Mean follow up of the cohort was 12.7±9.02 months. Mean HBP percentages were 77±37% and 72.2±42.1% for MDT and BSC, respectively (p=0.430). Mean HBP threshold (Volts) at implant was significantly lower with BSC vs MDT (0.85±0.58 vs 1.84±1.06, p=0.01), and similar after follow up (1.01±0.91 vs 1.32±0.73, p=NS). There were no statistically significant differences between mean HBP threshold at implant compared to follow up for both manufacturers. Interestingly, mean battery longevity for BSC vs MDT generators was significantly higher (136±29.3 vs 90.5±29.1, p Conclusion Our results suggest HBP with MDT Select Secure 3830 lead is feasible with BSC generators. There is potentially greater battery longevity with BSC compared to MDT generators. Further studies are needed with greater numbers and longer follow up to confirm this finding. Funding Acknowledgement Type of funding sources: None.

Background In the past decade, catheter ablation (CA) has become a rapidly expanding treatment option for ventricular tachycardia (VT), however it is not commonly utilized for patients with post-myocarditis VT. We aimed to systematically review up-to-date evidence regarding feasibility, effectiveness, and safety of CA, with a specific focus on long-term relapse rate and procedural complications. Methods A structured electronic database search (PubMed, Embase, Cochrane) of the scientific literature was performed for studies describing outcomes at up to 7.3 years after CA. The primary outcome measured was VT recurrence post-ablation. Procedural success was defined as freedom of ventricular arrhythmias (at the end of follow-up after an ablation procedure). The secondary outcome was significant procedural complications which included procedural death, stroke, cardiac tamponade, acute myocardial infarction, major vascular complications, and major bleeding, assessed on a study-by-study basis. Results A total of 186 patients were included in analysis with most patients (88%) being male. Over the follow up period there was a 18% relapse rate (n=34) (Confidence Interval (CI); 0.12–0.24, I2≈0, p=0.77) with the majority of patients remaining VT free for the duration of follow up. Only one study recorded the percentage of re-do procedures. The overall procedural complication rate was 3.0% (n=7, (CI; 0.01–0.07, I2≈0, p=0.44) and of note, there were no peri-procedural deaths or heart transplant surgeries reported. However, a single study reported a mortality of 10% (n=2) during the follow up period. Conclusions CA is an effective and durable long-term therapeutic strategy for post myocarditis VT patients with limited relapse rate and very low complication rates based on these non-randomised data. Larger randomised-controlled trials with standardised treatment and long follow-up are required to compare CA versus conventional treatment in the post-acute myocardial phase. Funding Acknowledgement Type of funding sources: None. Relapse rate during follow-upProcedural complication rate

Introduction We have investigated orofacial pain in a prospective cohort of obese and normal-weight subjects undergoing fixed-appliance orthodontic treatment. Methods Fifty-five subjects (27 males, 28 females) mean age 15.1 (1.6) years and mean body mass index 30.2 (3.5) in obese and 19.4 (2.2) kg/m2 in normal-weight groups were followed for 1 week after appliance placement. Primary outcome was maximum-pain measured using a 100-mm visual analogue scale. Secondary outcomes included mean pain and oral analgesic consumption. Results Mean maximum pain for the total sample was 73.7 (standard deviation 14.8; 95% confidence interval 69.8-77.7) mm with no significant differences among groups (P = 0.247). However, mean maximum pain was higher at all time-points for the obese group and significant at 72 hours (P = 0.034). Total analgesia consumed by the obese group was also significantly higher than normal weight (P = 0.041). Multivariable regression found the only significant predictor for mean pain was time. After adjusting for confounding, obesity was associated with higher (+4.47 mm) mean pain at each time-point (P = 0.018). A significant association existed between obesity and total analgesic consumption (univariable-analysis, P = 0.035; multivariable analysis, P = 0.023). After accounting for confounders, obese patients were associated with taking a higher quantity of oral analgesics. Conclusions We found a trend towards increased mean pain and an association with increased analgesic consumption in obese subjects during the first week following fixed-appliance placement.

Summary Objective This cross-sectional study aimed to explore the level of knowledge and expectations people deciding on a future orthodontic treatment have about post-orthodontic retention and to investigate the influence of sociocultural characteristics. Material and methods A total of 227 consecutive people involved as legal decision maker (as patient, parent, or legal guardian) for a prospective orthodontic treatment (mean age 37.1 years; 37.3 per cent male) received before their first appointment a questionnaire to assess their knowledge and expectations about post-orthodontic retention. Data were analysed descriptively, whereas predictors were identified with logistic regressions at P value of less than or equal to 0.05. Results Among the 220 responders, 46.3 per cent (n = 99) knew that retention appliances are used after orthodontic treatment and 52.8 per cent (n = 113) believed perfect results can guarantee stability, whereas at the same time, 77.8 per cent (n = 168) knew that teeth can move on their own without any orthodontic appliances. The majority considered stability of the orthodontic result important or extremely important (94.5 per cent; n = 206), preferred bonded over removable retainers (67.2 per cent; n = 133), believed the orthodontist to be primarily responsible for a stable result (73.2 per cent; n = 158), and found it appropriate to charge for recall visits (72.9 per cent; n = 153). Participants’ gender, age, education, nationality, and past orthodontic experiences within the close family significantly influenced answers. Limitations The setting of a single-centred survey conducted in one university moderates the generalizability of the portrayed results. Conclusions Although stability of orthodontic treatment results is very important to people deciding about a prospective orthodontic treatment, knowledge regarding the need for post-orthodontic retention varies and may at times be contradictious. Sociocultural factors seem to influence the level of knowledge and the expectations on post-orthodontic retention.

Aim: The validity of meta-analysis is dependent upon the quality of included studies. Here, we investigated whether the design of untreated control groups (i.e. source and timing of data collection) influences the results of clinical trials in orthodontic research. Materials and methods: This meta-epidemiological study used unrestricted literature searching for meta-analyses in orthodontics including clinical trials with untreated control groups. Differences in standardized mean differences (ΔSMD) and their 95% confidence intervals (CIs) were calculated according to the untreated control group through multivariable random-effects meta-regression controlling for nature of the interventional group and study sample size. Effects were pooled with random-effects synthesis, followed by mixed-effect subgroup and sensitivity analyses. Results: Studies with historical control groups reported deflated treatment effects compared to studies with concurrent control groups (13 meta-analyses; ΔSMD = −0.31; 95% CI = −0.53, −0.10; P = 0.004). Significant differences were found according to the type of historical control group (based either on growth study or clinical archive; 11 meta-analyses; ΔSMD = 0.40; 95% CI = 0.21, 0.59; P < 0.001). Conclusions: The use of historical control groups in orthodontic clinical research was associated with deflation of treatment effects, which was independent from whether the interventional group was prospective or retrospective and from the study’s sample size. Caution is warranted when interpreting clinical studies with historical untreated control groups or when interpreting systematic reviews that include such studies. Registration: PROSPERO (CRD42015024179). Conflict of interest: None.

Background: Although Rapid Maxillary Expansion (RME) has been used for over a century, its effect on upper airways has not yet adequately been assessed in an evidence-based manner. Objective: To investigate the volumetric changes in the upper airway spaces following RME in growing subjects by means of acoustic rhinometry, three-dimensional radiography and digital photogrammetry. Search methods: Literature search of electronic databases and additional manual searches up to February 2016. Selection criteria: Randomized clinical trials, prospective or retrospective controlled clinical trials and cohort clinical studies of at least eight patients, where the RME appliance was left in place for retention, and a maximum follow-up of 8 months post-expansion. Data collection and analysis: After duplicate data extraction and assessment of the risk of bias, the mean differences and 95 per cent confidence intervals (CIs) of upper airway volume changes were calculated with random-effects meta-analyses, followed by subgroup analyses, meta-regressions, and sensitivity analyses. Results: Twenty studies were eligible for qualitative synthesis, of which 17 (3 controlled clinical studies and 14 cohort studies) were used in quantitative analysis. As far as total airway volume is concerned patients treated with RME showed a significant increase post-expansion (5 studies; increase from baseline: 1218.3mm3; 95 per cent CI: 702.0 to 1734.6mm3), which did not seem to considerably diminish after the retention period (11 studies; increase from baseline: 1143.9mm3; 95 per cent CI: 696.9 to 1590.9mm3). Limitations: However, the overall quality of evidence was judged as very low, due to methodological limitations of the included studies, absence of untreated control groups, and inconsistency among studies. Conclusions: RME seems to be associated with an increase in the nasal cavity volume in the short and in the long term. However, additional well-conducted prospective controlled clinical studies are needed to confirm the present findings. Registration: None. Funding: Australian Society of Orthodontics Foundation for Research and Education Inc.