Impacted maxillary canine: Assessment of prevalence, severity and location of root resorption on maxillary incisors: A retrospective CBCT study.

BACKGROUND: The maxillary permanent canine is one of the most frequently impacted teeth, which often requires multidisciplinary management. A common complication of canine impaction is root resorption of the adjacent dentition. The aim of this retrospective study was to report the prevalence of root resorption of maxillary incisors adjacent to impacted maxillary canines from small volume CBCT images by trained clinicians. A secondary objective was to report the location and severity of root resorption. MATERIAL AND METHODS: CBCT images of patients with impacted maxillary canines (unilateral and bilateral) who attended a joint orthodontic/surgical multidisciplinary clinic were screened. Descriptive statistics were used to investigate associations of patient characteristics and presence of root resorption. Generalized estimating equations (GEE) logistic regression model were used to identify predictors of root resorption. RESULTS: In all, 148 impacted maxillary canines (122 patients) were analysed. The majority of patients were under 18 years of age (71.6%) with impacted canines present in more females (68.2%) than males (31.8%). Maxillary lateral incisors showed the highest prevalence of root resorption (38.5%). The apical region was the most common location of resorption for lateral incisors (20.9%) with a variable degree of severity evident: slight (10.1%), moderate (15.6%), and severe (12.8%). Although no significant predictors of root resorption were identified, a weak association was evident for age and root development. CONCLUSIONS: In this cohort of patients, the roots of maxillary lateral incisors are most likely to suffer from root resorption in the presence of an impacted maxillary canine. Clinicians should consider the extent, location and severity of resorption of adjacent teeth when planning treatment decisions and mechanics in cases of impacted maxillary canines.

Prognostic factors, outcomes, and complications for dental autotransplantation: an umbrella review.

BACKGROUND: Dental autotransplantation (DAT) is a biological way of replacing missing or compromised teeth for patients. The techniques often necessitate a multi-disciplinary approach. The prognosis and success of the procedure may be impacted by variable factors in varying degrees. OBJECTIVE: Evaluating outcomes and complications of DAT, including prognostic factors using an umbrella review. SEARCH METHODS: Six databases were searched for all relevant systematic reviews published up to 30 June 2022. No restrictions were applied to language or publication date. SELECTION CRITERIA: Systematic reviews and meta-analyses of DAT studies. DATA COLLECTION AND ANALYSIS: Identification, screening, eligibility, and quality assessment using the AMSTAR 2 tool were performed independently by two authors (M.C. and S.A.). Two studies (20%) scored moderate, six studies (60%) scored low, and two studies (20%) scored critically low. Data were analysed using a random effects meta-analysis, and meta-regression was performed to investigate the effect of open and closed apices on the dependent variables. The results were summarised as relative risk ratios. RESULTS: A total of 310 studies were eligible for inclusion, of which 20 studies were selected for full-text evaluation. Ten systematic reviews were included, 9 of which had a meta-analysis. Overall findings suggest that DAT offers favourable success and survival rates. Meta-regression results indicate that a closed apex increased the proportion of ankylosis and resorption, reduced survival but had no effect on success during the observational period. LIMITATIONS: A varying degree of heterogeneity and bias was present in all systematic reviews. The samples of donor teeth included in the systematic reviews also varied morphologically. CONCLUSIONS: DAT is a technique-sensitive procedure requiring a multidisciplinary team, vigilant case assessment and thorough consideration of the respective prognostic factors involved. Despite methodological limitations reported across studies, DAT shows favourable success and survival rates, with a distinctive advantage of bone induction and soft tissue thickness preservation, and should, therefore, be considered as a viable treatment modality. Standardisation of clinical guidelines and practice are highly recommended. REGISTRATION: CRD42020202484.

Aligning orthodontic education: Investigating the use of a digital app to improve the performance in managing orthodontic problems.

INTRODUCTION: General dentists are qualified to manage orthodontic emergencies within their scope of practice. This may involve advice, hands-on intervention or referral to a specialist orthodontist. This study aimed to assess the effect of an orthodontic app on dental undergraduates' ability to manage common orthodontic issues. In addition, this study aimed to determine the confidence of dental students in finding information related to orthodontic emergencies (CFI) as well as their confidence in managing orthodontic emergencies (CMOE). MATERIALS AND METHODS: Students were randomised into one-of-three groups, an app group, an internet group and a closed-book, exam-style group. All participants self-reported their CFI and CMOE. Following this, all participants were asked to complete a multiple-choice question (MCQ) paper based on clinical orthodontic scenarios. In addition, the app group were instructed to complete an app usability questionnaire (MAUQ). RESULTS: Approximately, 91.40% of students (n = 84) had not received clinical training in managing orthodontic emergencies, and 97.85% (n = 91) had not managed an orthodontic emergency clinically within the last 6 months of their training. The mean score for CFI was 0.10 out of 1.0 (SD 0.11) and CMOE was 0.28 out of 1.0 (SD 0.23). Statistically significant better MCQ scores were found in the app group, and no statistically significant difference was found between the internet and exam-style group. CONCLUSIONS: This study is the first to consider the use of an orthodontic app to aid in the management of orthodontic issues. It has practical implications for how mobile apps can aid in learning and can be incorporated into the wider dental field.

Comparison of automated digital Peer Assessment Rating compared with measurements performed by orthodontists, dental students, and assistants using plaster, additive manufactured, and digital models.

BACKGROUND: There are little scientific data on fully automated Peer Assessment Rating (PAR); this study compares a number of PAR scoring methods to assess their reliability. OBJECTIVES: This investigation evaluated PAR scores of plaster, 3D printed, and virtual digital models scored by specialist orthodontists, dental auxiliaries, undergraduate dental students,and using a fully automated method. MATERIALS AND METHODS: Twelve calibrated assessors determined the PAR score of a typodont and this score was used as the gold standard. Measurements derived from a plaster model, a 3D printed model, and a digital model, were compared. A total of 120 practitioners (specialist orthodontists, dental auxiliaries, and undergraduate dental students, n = 40 each) scored the models (n = 10) per group. The digital models were scored twice, using OnyxCeph (OnyxCeph) and OrthoAnalyzer (3Shape). The fully automated PAR scoring was performed with Model+ (Carestream Dental). RESULTS: Neither type of model (P = 0.077), practitioner category (P = 0.332), nor interaction between the two (P = 0.728) showed a statistically significant effect on PAR scoring. The mean PAR score and standard deviation were comparable for all models and groups except the automated group, where the standard deviation was the smallest (SD = 0). Overall, the greatest variation was observed for weighted overjet and contact point displacements. CONCLUSIONS: PAR scoring using plaster, 3D printed, and digital study models by orthodontists, dental auxiliaries, dental students, and a fully automated method produced very similar results and can hence be considered equivalent. Automated measurements improve repeatability compared with all groups of practitioners, but this did not reach the significance level.

Cost-effectiveness of orthodontics: a systematic review.

BACKGROUND: Health economic evaluation is a methodology to maximize health benefits and minimize opportunity costs and is of increasing importance in informing resource allocation decisions in healthcare. OBJECTIVE: This systematic review aims to assess the availability and quality of economic evaluations of any orthodontic interventions and summarize the conclusions of these studies. SEARCH METHODS: A thorough search of the literature was carried out including terms related to orthodontic interventions and economic evaluation between January 2000 and February 2022. MEDLINE, EMBASE, SCOPUS, Web of Science, NHS Economic Evaluation Database, and Cochrane were searched. Grey literature was searched and further hand-searching was performed on the reference lists of relevant systematic reviews. SELECTION CRITERIA: Studies on cleft lip and palate surgery and sleep apnoea were excluded due to the multi-disciplinary nature of these conditions which might alter the applicability of the result to orthodontic interventions. Two independent reviewers selected studies for inclusion. DATA COLLECTION AND ANALYSIS: Data extraction was carried out through full text analysis of included studies by two authors. The quality of each study was assessed according to the Drummond 10-point Checklist and the National Institute for Health and Care Excellence (NICE) Quality Appraisal Checklist for Economic Evaluations. Characteristics and conclusions of included articles were descriptively summarized. RESULTS: Sixteen articles met inclusion criteria. Most of the included articles were trial-based studies, with only one model-based study. Orthodontic interventions assessed included crossbite correction, functional appliance treatment and orthognathic surgery. Most studies were carried out in Europe and specifically in Sweden. The quality of included studies was generally low with 69% of studies reported as having serious limitations according to the NICE Checklist. CONCLUSION: This review highlighted a lack of economic evaluations for orthodontic interventions, and limitations of existing economic evaluations. Recommendations on future research are provided. REGISTRATION: The protocol for the systematic review was registered on the NIHR Database (www.crd.york.ac.uk/prospero, CRD42021220419).

Quality-of-life improvement, psychosocial benefits, and patient satisfaction of patients undergoing orthognathic surgery: a summary of systematic reviews.

BACKGROUND: Function, aesthetics, and social and psychological well-being are all important aspects for patients undergoing orthognathic surgery. OBJECTIVE: To evaluate the impact of orthognathic surgery on patient perception and quality of life before, during and after treatment. SEARCH METHODS: All relevant systematic reviews published up to 31st July 2020 have been searched via MEDLINE via OVID, Scopus, EMBASE, Web of Science, Cochrane Database of Systematic Reviews, PsycINFO, AMED (Allied and Complementary Medicine Database), and PubMed.Ongoing systematic reviews and grey literature were eliminated. A manual search was also undertaken, and no restrictions were applied to language or publication date. SELECTION CRITERIA: Systematic reviews involving dentofacial deformities related to systemic disorders, cleft lip and palate, facial trauma, and syndromes affecting cranial and dentofacial structures were excluded. DATA COLLECTION AND ANALYSIS: Identification, screening, eligibility, and quality assessment [using the AMSTAR 2 tool (A Measurement Tool to Assess Systematic Reviews)] were performed by two authors independently. Data were synthesized qualitatively using thematic analysis. RESULTS: A total of 662 eligible studies were obtained of which 24 studies were selected for full-text evaluation, resulting in 12 eligible systematic reviews. LIMITATIONS: Due to heterogeneity of data, quantitative analysis was not possible. CONCLUSIONS AND IMPLICATIONS: Aesthetics and function are the main motives for seeking orthognathic surgery. Patient assessment before, during, and after orthognathic surgery is necessary for a thorough evaluation of self-perception and satisfaction throughout treatment. While psychological and social domains improved after orthognathic surgery treatment, the quality of life can deteriorate transiently during the pre-surgical orthodontic phase of treatment. A standardized assessment tool needs to be developed to assess quality-of-life changes consistently and provide comparable results. REGISTRATION: CRD42020199091.

Clinical communication in orthodontics: Any questions?

OBJECTIVE: To measure patient-perceived standards of clinician communication and identify elements of deficient performance. Good communication can improve the quality of care, patient satisfaction and compliance with treatment. DESIGN: Cross-sectional questionnaire service evaluation. SETTING: Two university dental hospital orthodontic departments. PARTICIPANTS: Any patients aged 10 years and over attending the orthodontic department for treatment or consultation were eligible for inclusion. Patients who required third-party translation services were excluded. METHODS: Clinicians provided the modified 15-item Communication Assessment Tool (CAT) to up to five patients in a clinical session. A front sheet for clinician characteristics was used and anonymised with a unique identifier. Univariable logistic GEE models examined associations among responses and clinician characteristics. RESULTS: There were 55 clinicians with 204 patient responses. The overall percentage of '5=excellent' ratings was 88% (SD 0.16). The lowest scoring item was 'encouraged me to ask questions' (55.8%). Based on clinician characteristics, there were lower odds of an excellent response for certain CAT items. There were higher odds of an excellent response if English was not the clinician's first language (1.05; 95% confidence interval = 1.00-1.09; P=0.03). CONCLUSION: There is a high standard of patient-clinician communication in the hospital orthodontic setting. Key areas of communication that require attention include encouraging patients to ask questions, talking in terms they can understand, recognising their main concerns and involving them in the decision-making process. The results of this study can be used to inform communication skills training and be replicated in similar dental settings (primary and secondary care) as part of quality improvement.

The Effects of Additional Filtration on Image Quality and Radiation Dose in Cone Beam CT: An In Vivo Preliminary Investigation.

Purpose: The aim of this study was to investigate the effect of reduced radiation doses on the image quality of cone-beam computed tomography scans and the suitability of such imaging for orthodontics, oral surgery, dental implantology, periodontology, and endodontology. Materials and Methods: Cone-beam computed tomography scans of a live patient were performed using seven attenuation filters with increased thickness to decrease the effective radiation dose from 22.4 to 1.8 µSv, and the effects of different radiation doses on image quality were further analysed. Quantitative image quality was calculated using dedicated measures, such as signal and contrast-to-noise ratio and sharpness. A panel of five certified raters assessed the cone-beam computed tomography scans qualitatively. Nine anatomical structures relevant to dentistry were identified, and the overall acceptance was assessed. Results: Linear reduction of the effective radiation dose had a nonlinear effect on image quality. A 5-fold reduction in the effective dose led to acceptable quantitative and qualitative image quality measures, and the identification rate of dental anatomical structures was 80% or greater. The use of less than 40% of the reference dose was unacceptable for all dental specialties. Conclusions: The ideal radiation dose for specific diagnostic requirements remains a patient-related and specialty-related decision that must be made on an individual basis. Based on the results of this study, it is possible to reduce exposure in selected patients, and at the same time obtain sufficient quality of images for clinical purposes.

Adherence to RCS recommendations for extraction of first permanent molars in a teaching hospital: To compensate or not to compensate?

OBJECTIVE: To observe whether paediatric dentists and orthodontists balance and compensate the extraction of first permanent molars (FPMs) in children aged 7-11 years. DESIGN: Service evaluation. SETTING: UK dental teaching hospital. METHODS: Retrospective analysis of FPM extraction patterns in patients aged 7-11 years that attended for extraction of FPMs from 1 January 2019 to 31 January 2020 (13-month period). RESULTS: A total of 194 patients were included and they collectively had 435 FPMs extracted. No balancing extractions to prevent dental centreline shifts and no lower FPM compensatory extractions were performed. Compensatory extraction of good prognosis upper FPMs were performed in 64% (94/146) of cases to avoid overeruption. Orthodontic input was sought for poor prognosis lower FPMs in 76% of cases compared to 51% for poor prognosis upper FPMs. CONCLUSION: Compensatory extraction of good prognosis upper FPMs to avoid overeruption appears to be a common practice at Guy's and St Thomas' Hospitals. There was also higher demand for orthodontic advice for cases presenting with poor prognosis lower FPMs compared to poor prognosis upper FPMs, which suggests that paediatric dentists may prefer for the final decision on upper FPM compensatory extractions to be made by an orthodontist, even with national guidelines available. More high-quality research on the topic is required to determine the necessity of this practice for achieving optimal long-term oral health in children.

Minimum intervention in orthodontics.

Minimum intervention is defined as the smallest value or number of interruptions. Intervention is defined as an action intended for a challenging situation to improve it or to prevent it from getting worse. This article defines what constitutes 'minimum intervention' in dentistry and specifically in orthodontics. It presents the clinical techniques that constitute the specialty of orthodontics and identifies the ones that are deemed as minimum interventions. This article also presents the scientific evidence backing several orthodontic techniques, rendering them acceptable by the profession over others with no or very poor scientific evidence, thus increasing the chances of suboptimal outcomes.

Survival probability of dental autotransplantation of 366 teeth over 34 years within a hospital setting in the United Kingdom.

INTRODUCTION: The purpose of this retrospective study was to evaluate 34 years' experience of autotransplantation of teeth during orthodontic treatment. METHODOLOGY: Treatment was completed at Queen Mary's Hospital, Sidcup, Kent, UK, during the period 1969-2003. A total of 366 teeth were transplanted in 314 patients. RESULTS: Canines totalled 78 per cent of all autotransplanted teeth; mean age of patient was 19.4 years. Survival probability for the first 5 years post-autotransplantation was 95 per cent, 94 per cent for the subsequent 5 years, and 88 per cent after 15 years. The maximum observation period was 34 years, the median was 2.0 years, and the mean was 3.51 (standard deviation = 3.68) years. Of the observed teeth, 10 failed and these were lost due to unsuccessful periodontal ligament regeneration and persistent mobility grade III (or greater). Apical pathology was observed in 16 per cent of all autotransplanted teeth. In 79 per cent of this subgroup, apical pathology was evident in the first 3 years post-operatively. Seventy per cent of all external resorption also occurred within the first 3 years. Internal resorption was rare but its occurrence was mostly observed between the second and sixth year post-transplantation. A minority of autotransplanted teeth [14 per cent (n = 51)] needed root canal therapy, and this was completed within the first 6 months post-transplantation. CONCLUSIONS: Autotransplantation can be a justified procedure with good survival probability. It can be considered an alternative to other treatments, such as prosthodontic replacement of teeth.

Occlusal height difference between maxillary central and lateral incisors: should aesthetic perception influence bracket placement?

BACKGROUND: The aim of this study was to verify anecdotal evidence that the maxillary central-to-lateral occlusal height difference (OHD) of more than 0.5 mm is a feature displayed in the majority of media and to discuss its implications for individualized orthodontic treatment planning. METHODS: Photographs of smiling female models were collected from a variety of printed advertisements and allocated to 3 groups (n = 30 each): 1 dental, 2 fashion and 3 orthodontics. Group 4 used female patient images from orthodontic textbooks, assuming an OHD of 0.5 mm between maxillary central and lateral incisors. OHD was assessed by measuring the incisor height on the photographs and using average values to establish height differences. RESULTS: The average maxillary central-to-lateral incisor OHD differences were 1.39 mm (dental literature), 1.34 mm (fashion advertisements), 1.23 mm (orthodontics) and 0.62 mm (orthodontic textbooks) respectively. The differences between the advertisement groups were not significant (P >  0.05), but for orthodontic textbooks they were (P <  0.001). CONCLUSIONS: Advertisers seem to prefer greater maxillary central-to-lateral OHD compared to commonly used bracket placement protocols. Therefore, discussing OHD at start of treatment is recommended; modification of commonly used bracket placement protocols may be helpful to achieve desired aesthetic outcome.

Examining Cardiomyocyte Dysfunction Using Acute Chemical Induction of an Ageing Phenotype.

Much effort is focussed on understanding the structural and functional changes in the heart that underlie age-dependent deterioration of cardiac performance. Longitudinal studies, using aged animals, have pinpointed changes occurring to the contractile myocytes within the heart. However, whilst longitudinal studies are important, other experimental approaches are being advanced that can recapitulate the phenotypic changes seen during ageing. This study investigated the induction of an ageing cardiomyocyte phenotypic change by incubation of cells with hydroxyurea for several days ex vivo. Hydroxyurea incubation has been demonstrated to phenocopy age- and senescence-induced changes in neurons, but its utility for ageing studies with cardiac cells has not been examined. Incubation of neonatal rat ventricular myocytes with hydroxyurea for up to 7 days replicated specific aspects of cardiac ageing including reduced systolic calcium responses, increased alternans and a lesser ability of the cells to follow electrical pacing. Additional functional and structural changes were observed within the myocytes that pointed to ageing-like remodelling, including lipofuscin granule accumulation, reduced mitochondrial membrane potential, increased production of reactive oxygen species, and altered ultrastructure, such as mitochondria with disrupted cristae and disorganised myofibres. These data highlight the utility of alternative approaches for exploring cellular ageing whilst avoiding the costs and co-morbid factors that can affect longitudinal studies.

Association between severity of hypodontia and cephalometric skeletal patterns: a retrospective study.

Objective: To assess if severity of hypodontia is related to a specific skeletal pattern. Study design: Lateral cephalometric radiographs and dental panoramic tomographs of 182 hypodontia patients were analysed. The severity of hypodontia was recorded and the sample was divided into groups with mild (n = 71), moderate (n = 56) and severe (n = 55) hypodontia. According to ethnicity, the sample was further subdivided into White Caucasians, African-British, and Arabian/Indian subgroups. Cephalometric measurements were used to quantify the skeletal discrepancy and vertical facial dimensions. Mean and standard deviation for each group were obtained for comparison and an analysis of variance (ANOVA) was carried out to assess the level of significance between the means of the readings in different severity groups. Results: In the white Caucasian group, increased severity of hypodontia, was related to a retrusive maxilla with concomitant reduction of A point, Nasion, B point (ANB), reduced mandibular plane angle and anterior lower facial height (P value: 0.0935-0.9371). For the Black-British and Arabian/Indian groups' findings were inconsistent, with no specific pattern as the number of missing teeth increased. Conclusion: The white Caucasian group followed a pattern that has previously been reported in other studies. For Black-British and Arabian/Indian groups' findings were inconsistent and no specific pattern emerged for different degrees of hypodontia.

Alignment efficiency and esthetic performance of 4 coated nickel-titanium archwires in orthodontic patients over 8 weeks: A multicenter randomized clinical trial.

INTRODUCTION: The objective of this 4-arm parallel study was to evaluate the alignment efficiency and esthetic performance of 4 coated nickel-titanium archwires over an 8-week period. METHODS: Patients in the permanent dentition requiring maxillary and mandibular fixed orthodontic treatment with a preadjusted edgewise appliance were eligible for inclusion. Patients attending 4 hospital departments (United Kingdom and Italy) were randomly allocated to 1 of 4 treatment interventions: (1) BioCosmetic (Forestadent, Pforzheim, Germany), 0.017 in; (2) Titanol (Forestadent), 0.016 in; (3) TP Aesthetic (TP Orthodontics, La Porte, Ind), 0.014 in; and (4) Tooth Tone (Ortho Organizers, Calsbad, Calif) 0.016 in. Block randomization with block sizes of 4 and 8 was used to ensure an allocation ratio of 1:1:1:1. The primary outcome was alignment efficiency determined by the reduction in Little's irregularity index (mm). Secondary outcomes were color change using the Commission Internationale de L'Eclairage L*a*b* system and percentage of coating loss. Blinding was only applicable to outcome assessment of alignment efficiency. Regression models with Sidak's multiple comparison of means were used to analyze the data. RESULTS: One hundred fifty patients (300 dental arches) were allocated to the treatment interventions, including 61 male and 89 female subjects with a mean age of 16.60 years. The average duration of follow-up was 63.65 days. Baseline characteristics for the archwire groups were similar. One patient was lost to follow-up. Five percent (n = 15) of the archwires fractured: BioCosmetic, 5.3% (n = 4); Titanol, 6.8% (n = 5); TP Aesthetic, 5.3% (n = 4); and Tooth Tone, 2.7% (n = 2). We analyzed 283 dental arches for alignment efficiency. There was no statistically significant difference for mean reduction in irregularity between the archwire groups (P = 0.627): BioCosmetic (n = 71), 3.86 mm (95% CI, 3.31-4.41); Titanol (n = 69), 4.51 mm (95% CI, 4.00-5.02); TP Aesthetic (n = 71), 4.13 mm (95% CI, 3.49-4.78); and Tooth Tone (n = 72), 4.21 mm (95% CI, 3.89-4.46). There was a statistically significant difference between archwire groups for color change (P = 0.001) and percentage of coating loss (P = 0.001), with BioCosmetic performing best in both parameters. CONCLUSIONS: There was no difference between the archwires for alignment efficiency. BioCosmetic performed statistically significantly better than did the other groups for both color change and coating loss. REGISTRATION: This trial was registered with the East Midlands NHS Research Ethics Committee (12/EM/0190). PROTOCOL: The protocol was not published before trial commencement.

Influence of interradicular and palatal placement of orthodontic mini-implants on the success (survival) rate.

BACKGROUND: The purpose of this retrospective cohort study was to investigate the success rates of orthodontic mini-implants (OMIs) placed in different insertion sites and to analyse patient and site- related factors that influence mini-implant survival. METHODS: Three hundred eighty-seven OMIs were inserted in 239 patients for orthodontic anchorage and were loaded with a force greater than 2 N. Two different insertion sites were compared: 1. buccal inter-radicular and 2. palatal, at the level of the third palatal ruga. Survival was analysed for location and select patient parameters (age, gender and oral hygiene). The level of statistical significance was set at p < 0.05. RESULTS: The overall success rate was 89.1%. There were statistically significant differences between insertion sites; success rate was 98.4% for OMIs placed in the anterior palate and 71% for OMIs inserted buccal between roots (p < 0.001). CONCLUSIONS: Success rate of OMIs was primarily affected by the insertion site. The anterior palate was a more successful location compared to buccal alveolar bone.

Anatomic landmarks and availability of bone for placement of orthodontic mini-implants for normal and short maxillary body lengths.

INTRODUCTION: Increasing numbers of orthodontic mini-implants are placed in the anterior maxilla. To our knowledge, bone levels and root proximity of patients with cephalometrically short maxillae have not been investigated before. The first, second, and third rugae were used as clinical reference lines, and the aim of this study was to measure bone availability in that area by comparing patients with short and normal maxillary body lengths. METHODS: The sample consisted of 21 patients in each group: short maxillary body length and normal maxillary body length. The patients' study models were bisected, and the outline of the palatal contour was marked on the surface. The models were scanned, and the palatal contours were superimposed on the palatal structures of their respective initial cephalometric headfilms, and the vertical and oblique bone levels of the sagittal plane were compared using the Student t test. The level of significance was set at P <0.05. RESULTS: Compared with maxillae of normal maxillary body length, less bone was available in maxillae of short maxillary body length. However, the differences did not reach clinical or statistical significance (P >0.05) at the third rugae. CONCLUSIONS: Almost equivalent average bone depth at the third rugae in patients with normal and short maxillary body lengths suggests that this site can be used for 8-mm long obliquely inserted orthodontic mini-implants.

Precision of Le Fort I osteotomy: planning versus outcome. A multi-centre retrospective study.

INTRODUCTION: The purpose of this study was to evaluate the accuracy of Le Fort I surgery by comparing planned surgical movements with actual outcomes. MATERIALS AND METHODS: A minimum number of seven consecutive cases that had undergone a Le Fort I osteotomy procedure alone or in combination with a mandibular osteotomy from six different hospital units in the East of England between 2009 and 2010 were identified. A total of 56 cases met the inclusion criteria where surgical splints were used and model surgery had been performed. Pre- and post-operative lateral cephalograms were digitised using Dolphin© imaging software (Version 10.0) and three cephalometric points were assessed to measure precision of surgical movements: A point (A-pt); Upper incisor tip (U1 tip); and Upper first molar occlusal point (U6 occ). The final position of the maxilla was compared to the planned position. RESULTS: In 71% of cases surgical movements were within 2 mm and 20% of this group were within 1 mm of the predicted position. The mean accuracy was 1.39 mm (SD 0.92 mm) for the former and 0.78 mm (SD 0.58 mm) for the latter. Accuracy correlated negatively with increased surgical complexity, particularly posterior differential impactions of the maxilla. There was no statistically significant difference between centres. CONCLUSIONS: Pre-operative surgical planning of Le Fort I osteotomies was generally accurate. This study demonstrates that different operators across six centres produced consistent surgical outcomes and this confirms previously reported data.

Bond strength of stainless steel orthodontic brackets bonded to prefabricated acrylic teeth.

OBJECTIVES: The purpose of this in-vitro study was to evaluate the force to debond stainless steel orthodontic brackets bonded to acrylic teeth using different combinations of adhesive and surface treatments. MATERIALS AND METHODS: One hundred prefabricated upper lateral incisor acrylic teeth were divided into 4 equal groups: Transbond XT® adhesive only (Group 1, control), Transbond XT® adhesive with sandblasting (Group 2), Transbond XT® adhesive with abrasion / + methyl methacrylate (MMA) (Group 3) and Triad® Gel only (Group 4). The force in Newtons (N) to debond the brackets was measured. One-way analysis of variance (ANOVA) and pairwise multi-comparison of means (Sidak's adjustment) were undertaken. RESULTS: The highest force to debond was recorded for Group 2 (275.7 N; SD 89.0) followed by Group 3 (241.9 N; SD 76.0), Group 1 (142.7 N; SD 36.7) and Group 4 (67.9 N; SD 21.1). Significant differences in bond strength measurements between the experimental groups were detected. Mean force values for the groups revealed no significant differences between Group 2 and Group 3 (p>0.05). CONCLUSIONS: Both sandblasting and surface abrasion/+ application of methyl methacrylate (MMA) in combination with Transbond XT® adhesive are recommended for bonding stainless orthodontic brackets to acrylic teeth.