Abstract
The abstracts have been selected and edited by Elizabeth Crawford and Howard Moseley, Eastman Dental Hospital, London, UK.
Aims:
This pilot study primarily aimed to identify if any aerosol is generated during orthodontic procedures, and to estimate the longevity of this effect. The secondary aims were to assess the intensity of the aerosol produced by taking into account the range of particle sizes and the effect of the use of water on increasing or decreasing the aerosols created.
Methods:
The authors used a closed-side surgery to carry out the experiments on a dental manikin with a standardised 1-mm layer of composite base placed on 28 teeth (including second molars). To remove the composite, a slow handpiece (SHP) (max 25,000 rpm) or fast handpiece (FHP) was used alongside high volume suction. The authors compared a standard debond, debond without air, debond with water coolant and fast handpiece, and bracket repair using a three-in-one air–water syringe. The surgery had approximately six air exchanges per hour and experiments were repeated procedures on different days over three weeks to minimise the effect of external potential confounding factors such as air exchange and air conditioning. An optical particle scanner was used to assess particulate matter always at a fixed position of 8 cm away from the central incisor. This was measured 10 min before and continued for 30 min after the procedure started. As the SARS-CoV-2 viron is 80–100 nm in diameter, only assessed particles > 80 nm were recorded, as smaller particles were thought to be irrelevant to viral transmission. Four categories for particle size were decided on, these were: very small = 0.08–0.26 μm; small = 0.26–0.9 μm; medium = 0.9–2.7 μm; and large = 2.7–10 μm. Mann–Whitney U tests were used to estimate the probability that the measurements during the procedure and the fallow period were significantly different.
Results:
Time taken for the various procedures was in the range of 4–11 min for debond using air, no air, water or a fast hand piece. Repair and washing of the enamel with the three-in-one air–water syringe took < 60 s. Most procedures lead to a statistically significant increase in aerosol concentrations in most size ranges. A standard debond (using a SHP with no air or water) showed short duration of increase in ‘very small’ and ‘small’ particles. Debonding using a SHP and additional air coolant generated similar particles to that of standard debonding. Debonding using a SHP, with water, led to large peaks, with the production of all particle sizes continuing through the experiment and a higher magnitude than during standard debonding. These particles remained present for several minutes after the end of the procedure. Using a FHP and water resulted in the greatest production of particles, with short sharp increases seen. Additionally, the repair (for only two teeth) also showed an increase in particle concentration for ‘very small’ and ‘small’; however this duration was much shorter, with the total increase much less compared to the other procedures carried out. The use of the three-in-one air–water syringe did not show any detectable increase in aerosol levels. Particle levels reduced to background levels within 5–10 min; therefore, given the additional clinical time taken for a debond (e.g. impression taking) a fallow period for orthodontic procedures may not be necessary.
Conclusion:
This study concluded that for orthodontic debonding with the current high SARS-CoV-2 risk a SHP should be used rather than a FHP, without the use of water. The use of the three-in-one air–water syringe was shown to be a low-risk procedure. Thus, for reducing the risk posed to patients and staff, in the settings described in the study, a fallow period of 5 min would be considered safe.
Comments:
This in vitro study demonstrated good efficacy and gives an excellent insight into an important topic for orthodontics, and the whole dental profession, during the COVID-19 pandemic. It adds to a limited body of evidence on aerosol generation during orthodontic procedures. However, the debonding of composite from acrylic teeth may vary in technique and time in comparison to removal from natural teeth. The authors considered that a salivary substitute was not used in this experiment, and this could have a significant influence on the aerosol produced in a clinical setting. The particle scanner was positioned close to teeth and while this will be the most concentrated area of aerosol production, it would also be useful to see the effects of the aerosol in other areas of the room.
Reference
Sergis A, Wade WG, Gallagher JE, Morrell AP, Patel S, Dickinson CM, et al. (2020) Mechanisms of atomization from rotary dental instruments and its mitigation. Journal of Dental Research. DOI: 10.1177/0022034520979644.
Readers may also be interested to read the above paper, which came out recently.
Aims:
This systematic review and meta-analysis aimed to review how effective miniscrews were in reinforcing anchorage during en-masse retraction of anterior teeth.
Methods:
The trial protocol was registered with PROSPERO. Planning and reporting was done using the Cochrane guidelines for systematic reviews. The trial had a clear PICO: the participants were patients of any age or gender, who required en-masse retraction of anterior teeth, using fixed orthodontic appliances following extraction of maxillary premolars. The treatment could be provided by GDPs, specialists or in a hospital environment. The treatment was required to be compared with another type of anchorage reinforcement, such as, headgear, nance appliance or transpalatal arch. The primary outcome was anchorage loss, defined as mesial movement of the upper first permanent molars (UFPM) in millimetres. Secondary outcomes included treatment and space closure duration, number of visits, quality of treatment, adverse effects and patient-reported outcomes. Studies included were randomised controlled trials (RCTs) published in English, with no restrictions on year, status or type. In vitro studies were excluded. Two authors conducted a comprehensive electronic search, alongside manual searches of leading orthodontic journals and bibliographic databases for ongoing and unpublished data. Authors were contacted for clarification of study designs. Study selection was carried out by two authors independently. In the case of disagreement, a decision was made via an open discussion with a third author. The Cochrane Collaboration tool was used to assess bias in the included studies. For data synthesis, a random effects model was used and the standardised mean difference with 95% confidence intervals (CI). Statistical heterogeneity was assessed using chi-square and I2 tests.
Results:
A total of 751 records were identified, with 717 excluded by the initial screening process. The full texts of 34 articles were read by the authors, with 27 excluded; a flow chart was included in the publication. Seven RCTs were included in the final analysis: six were single-centre, two-arm parallel trials; one was a multicentre, three-arm parallel trial; and all were performed in university settings. Four studies compared mini screws to transpalatal arches, three compared them to headgear and the three-arm trial compared nance, headgear and miniscrews. Four studies had a high risk of bias and three studies had an overall low bias risk. A total of 241 participants from six of the trials were included in the meta-analysis as they recorded the primary outcome appropriately. This equated to 250 miniscrews and 134 conventional anchorage reinforcement. The anchorage loss favoured miniscrews, with the standardised mean difference between the groups at 2.07 mm. This result did not change following the exclusion of studies with a high risk of bias (1.94 mm). The information recorded in the studies on secondary outcomes was limited. Overall treatment duration was recorded in two trials, meta-analysis using a fixed effects model showed a −1.10-month (95% CI = −3.98 to 1.79, P = 0.98, I2 = 0%) difference between the groups in favour of miniscrews. Two trials with a high risk of bias found no difference between the rate of space closure in the two groups. Peer assessment rating (PAR) was used to assess treatment quality in only one trial and the results were in favour of miniscrews in comparison with headgear. Only one study assessed patient perceptions of the appliances, the comments were more positive towards miniscrews compared to headgear and nance appliances.
Conclusion:
This systematic review and meta-analysis found that there is moderate quality evidence that anchorage reinforcement with miniscrews is more effective than with traditional anchorage methods including transpalatal arches and headgear. There is limited evidence that miniscrews obtain improved occlusal outcomes and are preferred by patients. However, these results are based on a low number of studies, some of which had a high risk of bias. Therefore, further high-quality research is required to improve the evidence on the effectiveness of using miniscrews for anchorage reinforcement.
Comments:
This was a well-designed systematic review and meta-analysis of a relevant issue to orthodontists with up-to-date research included. However, there is a risk of publication bias as the authors only searched for trials in English. There were also a low number of trials identified, some of which had a high risk of bias, alongside statistical heterogeneity. The trials included were all in the university setting, potentially reducing the generalisability of the results.
Aims:
This study aimed to assess if a relationship exists between facial size and/or shape, and mandible size and/or shape, with regards to body mass index (BMI) in children and adolescents.
Methods:
This was a retrospective cross-sectional study assessing pre-treatment patient records from the University of Illinois, USA. Participants were included if they were aged 9–19 years and had appropriate records available (height, weight and radiographs). Patients were excluded if they had craniofacial anomalies, cleft lip and/or palate, syndromes, endocrine disorders, previous or current medication that may affect growth, previous orthodontic treatment and if appropriate records were not available. BMI was calculated using height and weight measurements and participants were placed into BMI categories (underweight, normal weight, overweight and obese) using the Centre for Disease Control and Prevention guidelines. Twenty-two landmarks were identified on lateral cephalometric radiographs, and the landmark data analysed as a whole for facial shape and as a subset for mandibular shape in isolation. Cephalometric landmarking was carried out by a single investigator (blinded to BMI), intra-rater reliability was assessed as good using the Kappa statistic and a subset of landmarking was done by a second examiner to assess inter-rater reliability. Geometric morphometrics was used to quantify and analyse any differences in craniofacial morphology. Centroid size was used as a proxy for the overall size of the face and mandible, calculated as the square root of the summed squared distances of each landmark from the geometric centre of the landmark configuration. Principle component analysis (PCA) was used to assess face shape variance. The Kruskal–Wallis test was used to assess differences between size and shape related to obesity status. Regression analysis for each PC was run on BMI percentiles and one-way ANOVA testing was used to compare all PCs representing > 5% of the total variation with BMI category. The underweight participants were removed from analysis at this stage over concerns that a low BMI might influence facial growth. It was decided to also run additional analyses on mandibular landmarks in isolation as key differences in the mandible were noted for patients with a high BMI.
Results:
A total of 181 patients (95 females, 86 males) were included; 51% were within normal weight range and 45% were overweight or obese. The 4% who were underweight were excluded from the analysis. Six ancestry groups were included in the study: African American; Asian; Caucasian Non-Hispanic; Caucasian Hispanic; Multiracial; and Unknown. Obesity was observed most in African Americans and least in Asians. The condylion-pogonion measurement was statistically significantly larger in female overweight and obese patients (P < 0.001), with correlation analysis to control for age it remained the same. Again, for female patients, S-Na-Ss (P = 0.031) and S-Na-B-point (P = 0.042) were statistically significantly different between the BMI groups. No significant differences for linear and angular measurements were noted between the BMI groups in male patients. Facial shape did not correlate with BMI scores. Facial shape did correlate with ancestry, with African Americans showing a more protrusive maxilla compared to Caucasians and Asians. With regard to the mandible, participants with a higher BMI showed taller rami, an increase in corpus height and slightly less prognathic chins with more superior B points. Correlation analysis showed a low correlation between facial centroid and BMI when controlling for age. Mandibular centroid size and BMI, while controlling for age, showed a weak positive correlation.
Conclusion:
The results of this study did not support a relationship between a high BMI and alterations of the facial shape. There was limited evidence that a childhood increase in BMI may lead to accelerated timing of facial growth; however, as this study was cross-sectional, the findings cannot assess the degree of acceleration. Further longitudinal studies would add to the evidence to establish in more detail the effect of high BMI on the timing of facial growth.
Comments:
With the incidence of obesity increasing worldwide, it is useful as orthodontists to be aware of the effects it may have on facial growth. However, there was a large variation in the age of the participants included in this study who were at different stages of growth and, while the cephalometric analysis was blinded, it would have been possible for the examiner to see the soft-tissue outline, which could result in measurement bias. Some significant changes were made to the methodology, including the exclusion of underweight participants and the addition of extra analyses on the mandible, which were also a source of potential bias.