Dental caries is a significant disease world-wide and although a massive reduction in prevalence has occurred over the past 50 years, incidents of this disease persist (particularly on the occlusal or aproximal surfaces and concerning younger demographics). The main reason for the observed reduction is exposure to fluoride either though water fluoridation and delivery by dentifrice. Environmental exposure reduces incidence by incorporation into the mineral phase of the hard tissue and, as a result, increases the resistance of the enamel mineral to acid-induced demineralisation. Several mechanisms have been proposed in an attempt to explain the caries-inhibiting effects of fluoride however its influence on the balance between de- and re-mineralisation episodes appears to be the principal route by which fluorides exert their effects. Efforts geared towards the continual improvement of fluoride delivery systems have also been successful to some extent and thus further exploration shows promise of improving the anticaries efficacy further. However, a complication is met in that, in vivo, multiple factors interrelated and consequently, differences in the consortia within natural oral biofilms combined with unavoidable inter-individual variations confound clinical investigations and make the distinction between relevant aspects of the process difficult. One possible alternative strategy is the development of in vitro biological models to simulate this process to a point of reflecting the in vivo situation whilst retaining control over the parameters which are known to be crucial to the progression of the disease. To this end, the Constant-Depth Film Fermenter (CDFF) has emerged as powerful tool to potentially meet the needs of current in vitro research. However, due to the lack of an inter-disciplinary approach to multi-faceted disease process, the full potential of the CDFF has not yet been reached. Therefore, the CDFF model was applied to study of anti-caries strategies which aimed to increase the persistence of the fluorides within natural microcosm biofilms. Enamel lesions were successfully produced within this system and, using a combination of both biological and non-biological demineralisations systems, the effects of anticaries agents (calcium and fluoride) were also investigated for their effects on lesion progression or reversal. Sodium fluoride (NaF; 300 ppm F-) exposures exhibited an ambiguous response on the microbial community although definite anticaries activity. Conversely, calcium lactate pre-rinses (Ca-lactate; 100 mM) appears to possess some inhibitory activity on the biofilms produced within the model whereas a less effective anticaries activity was observed in comparison to NaF exposures alone. Thus, further investigation of the effects of Ca-lactate should be pursued. Operation of the CDFF was also further developed to meet the needs of this study and analyses were performed on an integrative basis in order to capture the physiochemical events which take place during caries lesion formation. Microcosm plaques were shown to be highly diverse with respect to their community although homology was found on the bias of their ultimate definition, cariogenicity. The synthesis of inorganic mineral reservoirs within microcosm biofilms holds great potential for augmenting the physiology of the plaque and for increasing the efficacy of fluorides for prevention of enamel demineralisation. Microcosm biofilms may also have an adaptive capacity which could result in predicable response patterns. Ultimately, a holistic approach to the study of caries within a biological context provides greater insight into the caries process than approaches which lack specific interactions for the purposes of assigning direct relationships. With the successful development of a fully functional enamel caries model, the possibilities are endless.

Background: British children are exposed to higher levels of unhealthy than healthy food advertising through the television programmes they watch (Boyland et al., 2011). Needless to say, television is one of the most powerful media through which products can be promoted (Coon et al., 2001). Cairns et al. (2013), in their systematic review, found that television food advertisements can have a direct effect on children’s dietary choices, behaviours and attitudes. Furthermore, evidence shows that children who spend more time watching television are at a greater risk of developing caries (Locker, 2000). Show and Smith (1999) found an increase in the frequency of consumption of unhealthy food and beverages which could be damaging to children’s dental health. Cairns et al. (2013) found food advertisements to be a significant and independent determinant of children’s food behaviours. Therefore, it is crucial to explore to what extent foods that are potentially harmful to dental health are being promoted on UK television. Aim: To examine the prevalence of advertising of food and beverages on UK television watched by children, with a specific focus on foods that are potentially detrimental to dental health. Materials and Methods: Television sampling: Data were collected from 352 hours of television recorded from the main commercial UK channel, ITV 1, between January and December 2012. One weekday and one weekend day every month (both from 6am-10pm, i.e. 16 hours each) were recorded. Of the targeted 384 recorded hours, 32 hours were missing due to recording errors. Coding: Recorded television hours were scanned and both food and non-food adverts were coded according to a coding scheme previously used in Boyland et al. (2011), Kelly et al. (2010) and Gantz et al. (2007), which included the type of programme in which the advertisement was shown, and peak and non-peak children’s viewing times. Food adverts were classified, based on their effect on general health, into core/healthy, non-care/unhealthy, miscellaneous foods. They were further classified based on their effect on dental health into foods that are potentially harmful (cariogenic and acidogenic food products) and not harmful to dental health. Results: 9151 adverts were coded. Food products were the second most commonly advertised products, which accounted for 16.7% of all adverts (n= 1532). Adverts for foods that are potentially harmful to dental health comprised nearly two-thirds of all food adverts (61%; n= 934) and of these, 96.6% were cariogenic foods. Adverts for cariogenic foods with high and very high sugar levels ( > 9 g/100g or 100ml) represented 44.7% of all cariogenic food adverts. Of the advertised food products with very high sugar levels, sticky foods (50%) were the most frequently advertised products. Soft drinks were the most commonly advertised acidogenic foods/drinks, representing 52.4% of all acidogenic foods/drinks advertised. During peak children’s viewing hours, foods that are potentially harmful to dental health comprised nearly two-thirds (65.9%) of all food advertisements shown, which was significantly higher than the proportion of adverts for foods non-harmful to dental health (34.1%) (p = 0.011). Although the proportion of adverts for foods potentially harmful to dental health was less than 1% during children’s programmes, those adverts were shown significantly more often during other programmes watched by children and young people, such as entertainment (25.9 %) and game shows (16.8 %)(p < 0.001). Conclusion: Children are exposed to a considerably high proportion of advertisements for foods that are potentially detrimental to their dental health during children’s peak viewing hours and also around programmes watched by young people. The direct effect of television food advertisements on children’s dietary choices (Cairns et al., 2013) and the increase in the risk of caries associated with an increase in time spent watching television (Locker, 2000) suggest the need to apply stronger regulations that help reduce children’s exposure to unhealthy food advertisements.

Background: All research involving human participants should have ethical approval and informed consent. There is no recent evidence on the incidence of reporting of compliance with these ethical criteria in orthodontic journals, nor is there evidence on which factors predict the compliance of Randomised Controlled Trials (RCTs) with ethical approval and informed consent. Aims: This study aimed to: • Assess the number of Randomised Controlled Trials and Controlled Clinical Trials (CCTs) published in the American Journal of Orthodontics and Dentofacial Orthopedics, Angle Orthodontist, European Orthodontic Journal and Journal of Orthodontics (formerly British Journal of Orthodontics) between 1st January 2001 and 31st December 2010. • Determine the number of these papers which recorded having obtained ethical approval and informed consent. • Determine the number of authors, number of centres, location, involvement of a statistician, year of publication and the presence of “random*” in either the title or abstract or body of the RCTs. • Determine whether the factors above influenced an RCT’s likelihood of having recorded ethical approval and informed consent. • Determine the sensitivity of identifying RCTs in the four journals under consideration using various electronic search methods, through a MEDLINE search via PubMed and Ovid, for publication type “RCT” and PubMed free text search for “random* AND orthodontic”. Compare results with previously published findings. • Compare the electronic search methods with handsearching as the gold standard. Design: Retrospective observational study. Data Sources: Articles published between 1st January 2001 and 31st December 2010 in the American Journal of Orthodontics and Dentofacial Orthopedics (AJODO), The Angle Orthodontist (AO), European Journal of Orthodontics (EJO) and Journal of Orthodontics (JO) (formerly British Journal of Orthodontics). Sample: All CCTs and RCTs published in the AJODO, AO, EJO and JO between 1st January 2001 and 31st December 2010 were included. Method: • RF passed the Cochrane Oral Health Group Handsearching test. • A search of all CCTs and RCTs published in the AJODO, AO, EJO and JO between 1st January 2001 and 31st December 2010 was performed. • The RCTs and CCTs were assessed for a statement that the paper had obtained ethical approval and informed consent. • The RCTs were further analysed to determine the following criteria: publication journal, number of authors, number of centres, location of origin, involvement of a statistician, year of publication, and whether random* was in the title or abstract or body of the article. Results: Over the ten year period 4748 articles were identified, of which 218 reported RCTs and 89 CCTs. RCTs comprised 4.6% and CCTs 1.9% of all articles published over that time period. Of the CCTs, 36% had reported both ethical approval and informed consent and 39.3% had neither. Of the RCTs, 48.6% had reported both ethical approval and informed consent and 27.1% had neither. Factors associated with an RCT reporting that ethical approval and informed consent had been obtained were: Number of authors (p<0.001), Random* in Title (p<0.001), Random* in Abstract not Title (p<0.001), Location of origin (p=0.001), Year of publication (p=0.003), The journal of publication (p=0.004) and Number of centres (p=0.008). A logistic regression analysis showed that the most significant indicators of ethical approval and informed consent having been reported were: Publication in the JO (p=0.018), 6 or more authors (p<0.001), Random* in the abstract not title (p=0.004) and Publication after 2004 (p=0.001). A comparison of handsearching with three commonly used electronic search methods showed that handsearching was more accurate. Ovid was significantly less sensitive than PubMed (OR 8.43, 95% CI 5.48, 12.97) missing 157 RCTs (72.0%), while PubMed missed 51 (23.4%). The free text PubMed search, using the terms orthodontic AND random*, was the most sensitive missing 45 RCTs (20.6%); though this was not statistically significant (OR 0.85, 95% CI 0.54, 1.34) Only 56 RCTs (25.7%) were found by all 3 electronic searches. However 37 RCTs (17%) were not identified by any of the electronic search strategies. Conclusions: The reporting of whether ethical approval and informed consent had been obtained are inadequately reported in papers reporting orthodontic RCTs and CCTs. RCTs published in the JO, those with 6 or more authors, with Random* in the abstract but not the title and those published after 2004, were most likely to have reported that ethical approval and informed consent had been obtained. Handsearching was more accurate than electronic searching and PubMed more sensitive than Ovid.

Aims: 1) To assess interviewers‟ and interviewees‟ perceptions and experiences of Multi-Station Interview (MSI) for selection of Orthodontic Specialty Registrars (StRs) to UK regional Orthodontic training programmes; 2) To assess Trainers‟ and Trainees‟ perceptions and experiences of National Recruitment (NR); 3) To explore trainers‟ and trainees‟ perceptions and experiences of WorkplaceBased Assessments (WBAs) in Orthodontic StR training in England. Design: Cross-sectional questionnaire based qualitative survey. Methods: The study was conducted in three phases. Phase I involved interviewers and interviewees attending National Recruitment for Orthodontic StRs in May 2012. Phase II was conducted in August 2013 and, involved the trainees who had been recruited through the first National Recruitment and their trainers. Phase III was conducted in August 2013 and involved trainees who had started their training in 2011 or 2012 under the new curriculum. Two questionnaires were designed for each phase, one for trainers and one for trainees. Statistical analysis included descriptive statistics and frequency distributions. Results: Phase 1: 88% (36/41) of interviewers and all interviewees (83/83) completed the questionnaires. Of the interviewers, 56% were male; their mean age was 45.5 years (95%CI 43.0, 48.0) and the mean time that they had been a consultant was 11.4 years (95%CI 8.7, 13.1). The interviewers thought that the interviews were fair, tested an appropriate range of competences, selected the best candidates to be appointed and would appoint the same people if repeated. Of the interviewees, 61% were female; their mean age was 28.9 years (95%CI 28.2, 29.6) and their mean time since they qualified as dentist was 5.6 years (95%CI 4.9, 6.3) with 78% qualifying from a UK university. The interviewees preferred MSI format, considered the questions easy to understand and thought that the MSI was fairer than traditional interviews. Phase II: 53% (96/180) of trainers and 73% (19/26) of the trainees completed the questionnaires. For these trainers, 53% were male and the mean time that they had been a consultant was 13.6 years (95%CI 11.97, 15.20). Of the trainers who answered the questionnaire, 76% had not been involved in the NR interview process, 81% of them agreed that trainers need some choice as to who is appointed to their unit; 73% agreed that the previous recruitment system gave them more ownership and responsibility for their trainees; 66% would rather have the post empty for a year, than accept a weak trainee. For the trainees, the majority of them (81%) agreed that the NR meant that they did not have to miss out on other job possibilities whilst waiting for the one they wanted; all the trainees agreed that the NR reduced the time-off work they needed for interviews and visits. Of the trainees who completed the questionnaire, 58% agreed that NR increased their choice about where they applied to train; however, 8 (42%) felt pressurised to preference more units than they would have applied to previously; 13 (68%) would like to have been interviewed by their prospective trainer(s) but 12 (63%) would not have preferred to apply through the previous regional recruitment process. The vast majority (83%) of the trainees were allocated to one of their top three preferences and 67% of them would rank the units in the same order again. Only about half (52.6%) of the trainees visited units that they preferenced although 90% of the trainees agreed that visiting the units helped them rank their preferences. Almost all of them, (95%), were happy with their allocated unit(s). Phase III: 42% (76/180) of trainers and 62% (46/74) of the trainees completed the questionnaires. Of the trainers, the mean time that they had been a consultant was 12.8 years (95%CI 10.98, 14.66). The gender of the trainers was equally distributed. About half of the trainers spent 0.25 PA per month undertaking WBAs for their trainee(s) although 88% of the trainers did not have any PAs in their job plan for WBAs. 55% of them used less than 25% of their SPAs sessions for WBAs. However, 17% of the trainers had to use more than 75% of their SPAs session to conduct WBAs. Of the 74 trainees iii | P a g e who answered the questionnaire, 74% were female. In District General Hospitals, 91% of the trainees arranged their own WBAs. On average, trainees spent an hour per month undertaking WBAs. The mean number of completed WBAs per year was 12 (SD 4.2; 95%CI 10.7, 13.7) with the mode being 10 WBAs. Almost all trainees, (33/34) had more than 80% of their WBAs undertaken by consultants. Most of the trainees, 41% (14/34) had 3 trainers to undertake their WBAs. Conclusions: 1) Interviewers were positive about the selection of candidates, fairness and conduct of the multi-station interview format. Interviewees were very positive about the organisation and fairness of the multi-station interview format. 2) Overall there was a statistically significant difference in trainers‟ and trainees‟ perception of the NR. 3) Overall there was no statistically significant difference in trainers‟ and trainees‟ perception of the WBAs, which were acceptable to the trainers and trainees.

The effect of post-brushing mouthwashes on salivary fluoride retention. Objective: To assess the effect of post-brushing mouthwashes on salivary fluoride retention. Methods: This was a three phase cross over study with thirty participants. Salivary F levels were measured before brushing with a 1450 ppm F toothpaste (Time 0) and after brushing, rinsing with water and then with one of either 0,225 or 500 ppm F mouthwash at time points 1,3,5,10,20,45,60 minutes using an ion-specific electrode. Results: Significant differences in mean fluoride retention over the 60 minute period were found for all three pair wise groups using paired t tests (p<0.001). A 2660% increase in salivary fluoride retention over the 60 minutes was found with the 500 ppm F mouthwash when compared with the 0 ppm F group. With the 225 ppm F group a 120% increase was found. Conclusion: The use of a fluoride mouthwash containing 225 ppm or 500 ppm produced a significant increase in salivary fluoride retention following brushing with 1450 ppm F toothpaste and rinsing with water. The use of the 500 ppm F mouthwash may be of particular benefit to those at high caries risk including orthodontic patients. The effect of varying fluoride concentration on remineralisation of bovine enamel in vitro. Objective: To assess the effect of varying fluoride concentration on the remineralisation of bovine enamel in vitro using the techniques of quantitative light induced fluorescence (QLF – D), multispectral imaging (MSI) and transverse microradiography (TMR). Methods: artificially produced enamel carious lesions were produced following immersion in demineralisation solution (pH 4.5) for 72 hours. Baseline analysis was carried out with quantitative light induced fluorescence (QLF – D), multispectral imaging (MSI) and transverse microradiography (TMR). Samples were then randomised, using a computer generated randomisation sequence to one of 5 groups for remineralisation: 0 ppm, 225 ppm, 500 ppm, 1450 ppm or 2800 ppm Fluoride. The experimental phase lasted for eight weeks with weekly imaging with QLF-D and MSI. A post remineralisation phase of TMR was then carried out. Results: Reliable results were obtained for QLF-D and MSI only due to problems with the preparation of the baseline TMR samples. The results from QLF-D and MSI indicated a significant change in mineral loss occurred over the eight week period. Groupwise differences were shown between the 2800 ppm group and the remaining groups only. However, this was in a negative direction indicating mineral loss not gain as would have been anticipated. It is likely that a true remineralisation process was not replicated in this study. However in comparison of QLF-D and MSI techniques moderate correlation between the results was seen. MSI found greater differences and at an earlier stage than QLF-D. Conclusion: No remineralisation effect was seen in this study. Moderate correlation between the QLF-D and MSI results was demonstrated with greater differences detected with MSI.

Objectives: To assess the effects of orthodontic treatment for Class III incisors in children and adolescents. Design: A Cochrane systematic review. Method: The following databases were searched up to 7th January 2013: Cochrane Oral Health Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via OVID, EMBASE via OVID. Selection criteria: All randomised controlled trials of orthodontic treatments to correct Class III incisors. Trials were eligible for inclusion in the review if they recruited children and/or adolescents (aged 16 or less) receiving orthodontic treatment to correct Class III incisors. Trials including patients with a cleft lip and/or palate or other cranio-facial deformity/syndrome were excluded as were trials that had recruited less than 80% children or adolescents or patients who had previously received surgical orthognathic treatment. Active interventions included: orthodontic braces, chin cups, facemasks, reverse headgear, bone-anchored appliances or any other intra or extra-oral appliance aiming to correct Class III incisors. Controls included: No treatment, delayed treatment, other active intervention. Types of Outcome Measures - Primary: Prominence of the lower front teeth (measured in mm or by any index of malocclusion). Secondary: Relationship between upper and lower jaw; psychosocial measures; patient satisfaction; jaw joint problems. Adverse effects: Health of the gums; damage to the teeth e.g. tooth decay. Outcomes were recorded at all ages reported. The results were reported according to the most common endpoints. Adverse effects were recorded and the results reported in descriptive terms. Data collection and analysis: The titles and abstracts of the search results were examined to exclude obviously irrelevant reports. Full text reports of potentially eligible studies were examined for compliance with the eligibility criteria. Screening of references, data extraction and assessment of the risk of bias of included studies, was performed independently and in duplicate by two review authors. The mean differences, with 95% confidence intervals, were calculated for continuous data. Meta-analysis was only used when studies of similar comparisons were reporting comparable outcome measures. A fixed-effect model was used. I2 statistics were used as measures of statistical heterogeneity. Results: Seven randomised controlled trials were included in this review. Of these, four reported on the use of a facemask, two on the chin cup, one on the tandem traction bow appliance and one on mandibular headgear. One study reported on both the chin cup and mandibular headgear appliances. Three trials (n=155) reported ANB differences immediately after treatment with a facemask when compared to an untreated control. The pooled data, for ANB difference, showed a statistically significant mean difference of 3.93 degrees (95%CI 3.46 to 4.39; P<0.0001) in favour of the facemask. There was significant heterogeneity between these studies (I2=82%). One well designed trial, with a low risk of bias, reported outcomes of the use of the facemask compared to an untreated control at 3 years’ follow-up. This showed that improvements in overjet and ANB were still present at 3 years. However, there was no evidence of improved self-concept. The remaining trials each evaluated a different comparison and reported different outcomes so no meta-analysis was possible. Conclusions: There is some evidence that the use of a facemask, to correct prominent lower front teeth in children, is effective when compared to no treatment on a short term basis. However, in view of the general poor quality of the included trials, these results should be interpreted with caution. Further randomised controlled trials, with long follow-up, are required.

Background: Information regarding the various factors that can influence the duration of orthodontic treatment has been investigated before; however, despite the increasing amount of evidence becoming available, controversy still exists. Therefore, this investigation was considered to be useful as additional information to the orthodontic literature. Aim: To determine factors associated with the duration of orthodontic treatment for patients with a Class II malocclusion treated with a functional/fixed appliance approach to treatment. Design: Retrospective, observational study. Setting: Orthodontic Department, Liverpool University Dental Hospital, UK. Method: Data were collected from the records of eligible patients. Inclusion criteria: Patients were included if they had: 1) Undergone a course of orthodontic treatment involving a first phase of treatment with the Twin-Block appliance between the 1st of January 2005 and 31st of December 2008; 2) A Class II dental malocclusion; 3) Required a functional/fixed orthodontic approach to orthodontic treatment; 4) Completed two phases of orthodontic treatment; 5) Records available in a satisfactory condition. Outcome measures: • Duration of the functional appliance phase of orthodontic treatment • Total duration of orthodontic treatment Results: The pre-treatment overjet was the only factor that had a statistically significant influence on the duration of the functional phase of the treatment (p= 0.016). The factors that were statistically significant predictors for the duration of the full course of orthodontic treatment were: the number of treating clinicians (p=0.001), the number of failed appointments (p=0.001), the chronological age of the patient (p=0.002) and whether the patient had extractions or not (p=0.021). Conclusions: 1. The only factor that had a statistically significantly influence on the duration of the functional phase of treatment was the overjet at the start of treatment (positive association). 2. The factors that had a statistically significantly influence on the total treatment duration were the: a) Number of the treating clinicians (positive association); b) Number of appointments the patients failed to attend (positive association); c) Chronological age of the patient (negative association); d) Presence or absence of dental extractions (positive association).

Title A randomised controlled crossover trial to assess the effectiveness of, preference for and length of structured reply letters when communicating with referring practitioners Statement “I have made this letter longer than usual as I lack the time to make it short” (Blasie Pascal 1623-1662) Objectives To identify whether : 1. Structured reply letters from consultants were more effective at communicating with and/ or preferred by practitioners when compared to consultants’ standard reply letters. 2. There were differences in the length of the two formats. Null Hypothesis No significant difference exists between practitioner’s awareness of key patient information when receiving either the structured consultant reply letter or the standard consultant reply letter. No significant difference exists between the word counts of the two letter formats. Design Randomised controlled crossover trial. Setting Liverpool University Dental Hospital (LUDH). Participants and methods Participants were recruited from practitioners referring orthodontic patients to LUDH. Seventy five practitioners were stratified by consultant and randomised in blocks to receive either the structured or standard letter first, followed by the alternative format six weeks later. For both groups, the word count was recorded by the secretaries. ‘Knowledge and satisfaction’ questionnaires were dispatched with the letters, completed by practitioners and returned to the department. Outcome measures The primary outcome measure was the practitioners’ awareness of the key information contained within the letter. The secondary outcome measure was the secretarial typing times for the letters. Results The response rate was 87%. There was a statistically significant improvement in practitioners’ awareness of their patient’s status (odds ratio 8.84 95% CI 1.08, 72.52) and the action required (odds ratio 4.13 95% CI 1.10, 15.45) after receiving the structured letter. Practitioners showed a strong preference (p<0.001) for the structured consultant reply letter which were statistically significantly shorter than the standard format with a mean difference of 108 + 10 fewer words (mean difference: 108: 95% CI -118.14, -97.86). Conclusions This trial demonstrated that there was a statistical significant improvement in practitioners’ perceptual and actual awareness of their patient’s status and any action required, having received the structured letter. The structured reply letters had significantly fewer words than the standard letter. Practitioners strongly preferred the structured reply letter format.

BACKGROUND: Demineralisation around orthodontic brackets is a considerable risk of orthodontic treatment. It can occur very early during treatment and involve a large number of teeth with aesthetic and dental health consequences. Early detection of demineralisation is very important in terms of treatment and prevention. The presence of bacteria is one of the requirements for demineralisation to take place and it is unclear whether the type of bacteria in the plaque or the quantity of certain types of bacteria are significant influences on demineralisation. AIM: To identify any general changes in the bacterial composition of dental plaque in adolescents undergoing fixed orthodontic appliance therapy. A secondary aim is to determine the incidence of white spot lesion development and if this was related to the identified red fluorescent plaque. STUDY DESIGN: Prospective longitudinal cohort study. METHODS: Fourteen 11 to 23 year old consecutive patients attending the Orthodontic Department of Liverpool University Dental Hospital were recruited for this study. ToothcareTM and QLF were used to identify red fluorescent plaque and enamel demineralisation on the labial surfaces of the anterior teeth before and after the placement of fixed orthodontic appliances. The bacterial composition of the red fluorescent supragingival plaque was determined by DNA extraction, polymerase chain reaction amplification of the 16r rRNA gene and denaturing gradient gel electrophoresis. 13 RESULTS: The incidence of white spot lesions was recorded as 4.2% of the total surfaces of the teeth included as detected with QLF, the development of white spot lesions was not associated with the presence of red fluorescent plaque. There were differences in the bacterial composition of red fluorescent supragingival plaque in terms of P. gingivalis, S. mutans and S. gordonii between different participants, although changes in the plaque composition between visits for the same participant was not significantly associated with the development of white spot lesions in adolescents. CONCLUSIONS: With the limitations of this study, the placement of fixed orthodontic brackets in adolescents does not significantly change the bacterial composition of red fluorescent supragingival plaque around the brackets and that the development of white spot lesions cannot be correlated to red fluorescent plaque alone.

Introduction: Recent studies have utilised cone beam computed tomography (CBCT) for the assessment of the volume of the nasopharyngeal airway space (Guijarro-Martínez and Swennen, 2013, Lenza et al., 2010, Woodside and Linder-Aronson, 1979, Chang et al., 2013). Some of these investigations are based on the analysis of slice data obtained from three dimensional (3D) radiographic images. The usage of a CBCT scan to measure the nasopharyngeal airway volume has drawbacks which include the effect of respiration and tongue position (Abbott et al., 2004), the impact of head posture, lordosis (cranio-cervical inclination) and mandibular morphology on the accuracy of measuring air oro-pharyngeal airways. In addition, published figures to date has not considered the detailed anatomical boundaries of the nasal cavity space, paranasal airway space and other pharyngeal sections collectively (Chang et al., 2013). Aims and objectives: The aim of the study was to assess the validity of the free access software package like ITK Snap in measuring the airways spaces, investigate, using CBCT, the three-dimensional effect of rapid maxillary expansion on the maxillary sinus, the lower part of the nasal cavity, the upper nasopharynx and the upper oropharynx (upper and lower retropalatal spaces), and to correlate the changes in these anatomical spaces with the measured RME appliance split, the dentoalveolar expansion and the gender of the subjects. Materials and methods: This study was carried out on seventeen patients (8 boys, 9 girls; mean age 12.6 + 1.8 years) who required maxillary expansion for the management of narrow upper dental arch. Sample size was calculated using the Researcher’s Toolkit calculator and this indicated that a sample size of 14 patients would produce an Alpha error level or confidence level at 95% and a Beta error level at 20%. Therefore, it was decided to recruit 17 subjects to overcome potential exclusion due to irreproducibility in the head orientation and lordosis. Pretreatment (T1) and immediate post-RME (T2) CBCT images were taken for all the patients. In all CBCT images, head orientation and lordosis were measured using OnDemand 3D software packages. Cases were excluded from the study if the difference in the head orientation and lordosis between the CBCT of T1 and CBCT of T2 was more than 5 degrees. The two scans, T1, T2, were orientated according to a specific protocol and superimposed on the cranial base to standarise the volumteric segemtation and measurements. The impact of RME was assessed by measuring, using ITK snap and OnDemand 3D software packages, the changes in the distance between the intermolar dentoalveolar width at level of molar alveolar crest (IMD), the magnitude of appliance expansion (AE), the volume of respiratory region or the lower part of the nasal cavity (LNC), the volume of the right and left maxillary sinus (RMS and LMS), the volume of the upper nasopharynx (UNP), the subdivisions of the upper oropharynx including the upper and lower retropalatal space (URP and LRP) at T1 and T2. Segmentation of the oro-naso-pharyngeal spaces into multiple segments allows a deailed localisation of the changes and aids in exclusion of any potential masking change of one airway space on adjacent or remote airway space as each segment is associated anatomically and physiologically to different function and/or disorder. The normality of the data was tested using Kolmogorov–Smirnov test. The reproducibility of meaurements was analysed using Paired t-test and interclass correlation coefficient. The volumteric and linear changes was assessed using Student t-test (P < 0.05) and Pearson correlation coefficients was used to test the correlation of these changes. Results: Bonded RME has an effective dentoalveolar expansion effect in growing patients (P=0.001) and produced a significant increase in UNP (P=0.045). There was a statistically significant reduction on the URP space (P=0.042), especially in males. There was strong correlation between the increase of the volume of the right and left maxillary sinuses (PCC=0.86) and between appliance expansion and dentolavelar expansion (PCC=0.75). Conclusions: ITK-SNAP software is a reliable package and a single threshold value (-450 grey) is an accurate value. Additionally, this software can be used to measure the size of bony defect in patient with cleft palate before secondary alveolar bone grafting. Bonded RME was an effective dentoalveolar expander in growing patients and the immediate expansion of LNC and UNP might be associated with a reduction in nasal resistance, improvement in the nasal breathing and it can be considered as an option for treatment of Paediatric Obstructive Sleep Apnea Syndrome. Findings of this dtudy showed that there is a sexual dysmorphisim secondary to RME but did not reach the statistical significance. Generally, the effect of the RME on the upper naso-oro-pharyngeal airway spaces followed a mushroom like pattern with the upper parts expanded, the middle part was significantly narrowed while the lower part was mildly, but insignificantly statistically, reduced. However, it is essential to consider that regardless of the benefit of the increase nasal patency of this orthopeadic procedure, it should not done merely for the above purposes solely but only when it is linked to a right indication for RME. A future studies could include a colour mapping for detailed assessment of changes in different part of the oro-naso-pharyngeal space, as the shape changes of the airway space is as important as volumetric changes. Finally, a further randomised clinical trial or comparative study with larger sample size and long term follow up would be beneficial in estimating the real impact of the RME on the airway confirm the findings of this study.