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.

Changes in the Transverse Dimension of the Maxillary Arch of 5-Year-Olds Born With UCLP Since the Introduction of Nationwide Guidance.

OBJECTIVE: To determine whether the transverse dimensions of the maxillary arch of 5-year-old children with unilateral cleft lip and palate (UCLP) have changed following centralization of cleft services in the United Kingdom. DESIGN: Retrospective cross-sectional study. SETTING: Digital analysis of UCLP maxillary dental casts. PARTICIPANTS: All available maxillary dental casts from 5-year-old participants of the Clinical Standards Advisory Group (CSAG, N = 114) and Cleft Care UK (CCUK, N = 175) studies. INTERVENTIONS: Quantitative measurements of the intercanine width (ICW), intermolar width (IMW), and the distance from the midline to the greater and lesser side canine (GC/LC) and greater side and lesser side second primary molar (GE/LE). Degree measurements of the greater and lesser arch form angles, arch length, anterior palatal depth (APD), and posterior palatal depth were also measured. MAIN OUTCOME: Differences between the transverse dimensions of the maxillary arch for the CSAG and CCUK cohorts. RESULTS: In 5 (ICW, IMW, LC, LE, and APD) of the 11 measurements, there was a statistically significant difference between the CSAG and CCUK cohorts. In all of these, the CCUK values were greater than CSAG. CONCLUSIONS: There have been small but positive improvements for the transverse maxillary dimensions since centralization of the UK cleft service.

Positional factors affecting the surgical management of impacted permanent mandibular canines.

OBJECTIVE: To assess which positional factors influence the decision to surgically remove or expose an impacted mandibular canine. Clinical and radiographic assessment are important considerations when treatment planning for the management of impacted mandibular canines. DESIGN: A cross-sectional study. SETTING: The Royal Surrey County Hospital, Guildford, UK. METHODS: The clinical notes and orthopantomogram radiographs were assessed for all patients aged 21 years or under who underwent surgical management of impacted mandibular canine teeth between 2017 and 2019. The following variables were recorded: angulation, horizontal position, vertical height, overlap of the adjacent tooth and bucco-lingual position of the canine. RESULTS: From the 67 patients and 77 canines included, surgical extraction was performed for 48 canines (62%) and surgical exposure was performed for 29 canines (38%). Chi-square and multivariable logistic regression revealed canine angulation to the midline, horizontal position of the canine root apex, vertical height of the canine crown and canine overlap of the adjacent tooth to be associated with the decision to remove or expose an impacted permanent mandibular canine (P < 0.001). The bucco-lingual position of the canine did not influence the decision to remove or expose an impacted permanent mandibular canine (P = 0.159). CONCLUSION: The decision to expose or remove an impacted mandibular canine is guided by its angulation, horizontal position and vertical position, and by the degree of overlap of the adjacent tooth. However, the bucco-lingual position is not related to the decision to surgically remove or expose an impacted permanent mandibular canine.

Microbial colonisation associated with conventional and self-ligating brackets: a systematic review.

BACKGROUND: Decalcification and gingivitis caused by plaque accumulation around brackets are common iatrogenic effects of fixed appliances. The influence of conventional versus self-ligating bracket design on microbial colonisation is unknown. OBJECTIVE: To assess the levels of microbial colonisation associated with conventional and self-ligating brackets. SEARCH SOURCES: Three databases were searched for publications from 2009 to 2021. DATA SELECTION: Randomised controlled trials comparing levels of microbial colonisation before and during treatment with conventional and self-ligating brackets were assessed independently and in duplicate. DATA EXTRACTION: Data were extracted independently by two authors from the studies that fulfilled the inclusion criteria. Risk of bias assessments were made using the revised Cochrane risk of bias tool for randomized trials. The quality of the included studies was assessed using the Critical Appraisal Skills Programme Checklist. RESULTS: A total of 11 randomised controlled trials were included in this systematic review. Six of the studies were found to be at low risk of bias and five presented with some concerns. The studies were considered moderate to high quality. Five trials reported no statistically significant difference in microbial colonisation between bracket types. The remaining studies showed mixed results, with some reporting increased colonisation of conventional brackets and others increased colonisation of self-ligating brackets. The heterogeneity of study methods and outcomes precluded meta-analysis. CONCLUSION: Of the 11 studies included in this systematic review, five found no differences in colonisation between conventional and self-ligating brackets. The remaining studies showed mixed results. The evidence is inconclusive regarding the association between bracket design and levels of microbial colonisation.

Patient reported experiences and treatment outcomes of orthodontic patients treated within secondary care settings in the South West of England during the COVID-19 pandemic.

OBJECTIVE: To assess the impact of the temporary cessation of orthodontic services on patients undergoing treatment during the COVID-19 pandemic. DESIGN: Two-phase multicentre service evaluation. SETTING: Secondary care orthodontic departments in the South West of England. MATERIALS AND METHODS: Phase 1 - Patient-Reported Experience Measure questionnaire (PREM). The questionnaire was distributed to patients who had undergone orthodontic treatment during the COVID-19 pandemic once services had resumed. Phase 2 - assessment of treatment outcomes, specifically with the Peer Assessment Rating (PAR) Index. A total of 280 PAR scores were obtained from a cohort of patients treated before and during the pandemic. RESULTS: A total of 711 PREM questionnaires were completed. Participants generally felt relaxed when visiting secondary care settings, orthodontic departments and whilst wearing orthodontic appliances during the pandemic. Nearly 40% of participants were concerned that the pandemic would impact on their treatment, particularly treatment length. Treatment outcomes revealed that patients treated before and during the pandemic experienced percentage PAR score reductions of 83.9% and 80.6%, respectively. Patients receiving treatment during the pandemic experienced longer treatment durations of 126 days. CONCLUSION: During the pandemic, low levels of anxiety were reported with respect to receiving orthodontic treatment in secondary care settings. Irrespective of the pandemic, a high standard of orthodontic treatment was provided. However, patient concerns regarding treatment length were justified.

Particulate production during debonding of fixed appliances: Laboratory investigation and randomized clinical trial to assess the effect of using flash-free ceramic brackets.

INTRODUCTION: The aim of this laboratory and randomized clinical trial was to investigate particulate production at debonding and enamel clean-up following the use of flash-free ceramic brackets and to compare them with non-flash-free metal and ceramic brackets. METHODS: In the laboratory study, brackets were bonded to bovine teeth. After 24 hours of immersion in water, the brackets were debonded, the adhesive remnant scores noted, and the enamel cleaned with the use of rotary instruments. Four bracket-adhesive combinations and 2 different enamel pretreatment regimens were tested, including metal and ceramic brackets (conventional, adhesive precoat [APC], and APC flash-free) and conventional acid etch and self-etching primer. Quantitative (mg/m3) and qualitative analysis of particulate production was made in each case. In the clinical trial, 18 patients treated with the use of fixed appliances were recruited into this 3-arm parallel-design randomized controlled trial. They were randomly allocated to 1 of 3 groups: experimental flash-free ceramic bracket or non-flash-free ceramic or metal bracket group. Eligibility criteria included patients undergoing nonextraction maxillary and mandibular fixed appliance therapy. At completion of treatment, the brackets were debonded, and the primary outcome measure was particulate concentration (mg/m3). Randomization was by means of sealed envelopes. Data were analyzed with the use of quantile plots and linear mixed models. The effect of etch, bracket, and stage of debonding of clean-up on particle composition was analyzed with the use of mixed-effects regression. RESULTS: In the laboratory study, the APC brackets produced the highest particulate concentration. Although statistically significantly higher than the metal and conventional ceramic brackets, it was not significantly higher than the ceramic flash-free brackets. In the clinical study, there was no statistically significant effect of bracket type on particulate concentration (P = 0.29). This was despite 3 patients with APC flash-free and 1 patient with conventional Clarity (with 1 bracket) having 1 or more ceramic bracket fracture at debonding requiring removal. No adverse events reported. CONCLUSIONS: Particulates in the inhalable, thoracic, and respirable fractions were produced at enamel clean-up with all bracket types. Although APC and APC flash-free brackets produced the highest concentrations in the laboratory study, there was no difference between any of the brackets in the clinical trial. REGISTRATION: The trial was not registered. FUNDING: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

National British Orthodontic Society (BOS) Orthognathic Audit 2017-2018.

OBJECTIVE: To carry out a UK national clinical audit of orthognathic acceptance criteria and information provided to orthognathic patients before treatment. DESIGN: National clinical audit. SETTING: Data collected using Bristol Online Surveys. PARTICIPANTS: Sixty-nine UK hospital orthodontic departments submitted data. METHODS: Data were collected at two time points using Bristol Online Surveys over a period of 12 months. These were before treatment at the first multidisciplinary clinic (MDT) and immediately after surgery. The data collected included: Index of Orthognathic Functional Treatment Need (IOFTN); Index of Orthodontic Treatment Need (IOTN); age; previous orthodontic treatment; attendance at an MDT; treatment times; and information provision. RESULTS: Eighty-five units agreed to take part in the audit with 69 submitting data, giving a response rate of 81%. The data from 3404 patients were uploaded, 2263 before treatment and 1141 immediately after surgery. Of patients, 91.07% had an IOFTN score of 4 or 5 and 88.73% had an IOTN score of 4 or 5. The mean age at the first MDT was 22 years in the first cohort and 21 years and 4 months in the second immediate post-surgery cohort. Of patients, 37.93% had undergone some form of previous orthodontic treatment, but only 0.28% had undergone previous orthognathic treatment; 96.93% had an MDT confirm that orthodontic treatment by itself was insufficient to adequately correct their functional symptoms. The average treatment time from bond up to surgery was 2 years and 6 months. With respect to information provision, patients received information from a number of sources, principally the British Orthodontic Society (BOS) patient information leaflets and the BOS website Your Jaw Surgery. CONCLUSIONS: In the UK, the majority of orthognathic cases fulfil the criteria for acceptance for NHS-funded orthognathic treatment, as outlined by the Chief Dental Officer's interim guidance on orthognathic treatment. This suggests any prior approval process would not be a good use of NHS resources in the commissioning of orthognathic treatment.

Color stability of nonpigmented and pigmented maxillofacial silicone elastomer exposed to 3 different environments.

STATEMENT OF PROBLEM: The color degradation of maxillofacial prostheses in clinical service requires their frequent renewal. How different materials compare is unclear. PURPOSE: The purpose of this in vitro study was to investigate the color stability of a nonpigmented and pigmented maxillofacial silicone when stored in darkness and exposed to accelerated aging in a weathering chamber and natural outdoor weathering. MATERIAL AND METHODS: M511 elastomer was colored with Spectromatch Pro colorants, stored in darkness, and exposed to accelerated aging and natural outdoor weathering for 1500 hours. Test groups included nonpigmented specimens (n=18), individually pigmented specimens (n=90), and Caucasian skin tone-colored specimens (n=18). The CIELab values of the test specimens were measured using the CM-2600d spectrophotometer (Konica Minolta Sensing) at base line (0 hours) and then every 100 hours up to 1500 hours of aging. Color changes (ΔE) were calculated based on the recorded CIELab values. All data were analyzed by using linear mixed models and the Sídák multiple comparison of means test (α=.05). RESULTS: A significant effect of time was found on the ΔE of all test specimens in all environments (P=.001). All pigmented M511 specimens demonstrated good color stability with maximum ΔE below the acceptability threshold of 2 ΔE when stored in darkness and exposed to outdoor weathering. However, nonpigmented specimens crossed this acceptability threshold when exposed to outdoor weathering with maximum ΔE values of 3.65. The greatest color changes were observed for all specimens when exposed to accelerated aging and most exceeded the acceptability threshold. Nonpigmented (ΔE, 4.86) and Indian yellow (ΔE, 5.20) demonstrated the highest color changes after 1500 hours. CONCLUSIONS: All environments resulted in visible color changes of nonpigmented and pigmented M511 elastomer. The lowest ΔE values were observed for specimens stored in darkness and the greatest for specimens exposed to accelerated aging. The organic pigment Logwood maroon demonstrated the best color stability with maximum ΔE values below the perceptibility threshold (PT) of 1 ΔE.

Development of a 3D printable maxillofacial silicone: Part II. Optimization of moderator and thixotropic agent.

STATEMENT OF PROBLEM: Conventionally, maxillofacial prostheses are fabricated by hand carving the missing anatomic defect in wax and creating a mold into which pigmented silicone elastomer is placed. Digital technologies such as computer numerical control milling and 3-dimensional (3D) printing have been used to prepare molds, directly or indirectly, into which a biocompatible pigmented silicone elastomer can be placed. PURPOSE: The purpose of this in vitro study was to develop a silicone elastomer that could be 3D printed directly without a mold to create facial or body prostheses by varying its composition. MATERIAL AND METHODS: The room temperature vulcanizing silicone composition was divided into 2 components which were mixed 1:1 to initiate polymerization in the printer before printing began. Different types of moderators and thixotropic agents were used, and the base composition was varied to obtain 11 formulations. The specimens were printed and polymerized from these formulations and tested for tear and tensile strength and hardness. Ten readings of the specimens were recorded for tear and tensile strength and 6 for hardness. Results were analyzed using ANOVA (α=.05). Visual assessment of uncured printed specimens was undertaken for 5 formulations to assess any differences in their ability to hold their shape after printing. RESULTS: The tear and tensile strength of the 11 formulations with varying moderators, thixotropic agents, and base compositions were statistically similar to each other (P>.05). Five of 11 formulations were chosen for the visual assessment as they had sufficient thixotropic agent to avoid slumping while printing. The specimens showed varied slumping behavior until they polymerized. The filler content was increased in the selected formulation, and the tear and tensile strength of the formulation was increased to 6.138 kNm-1 and 3.836 MPa; these increases were comparable to those of commercial silicones currently used for the fabrication of facial prostheses. CONCLUSIONS: The optimum combination of mechanical properties implies the use of one of the formulations as a suitable material for the 3D printing of facial prostheses.

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.

Efficiency and effectiveness of orthodontic treatment within United Kingdom secondary care: a service evaluation.

OBJECTIVES: To evaluate the efficiency and effectiveness of Orthodontic treatment in the National Health Service (NHS) hospitals in England and to identify factors that may be predictive of the duration of Orthodontic treatment and number of patients' visits. DESIGN: Retrospective service evaluation. SETTING: The orthodontic departments of two NHS hospitals. METHODS: The data were collected from the clinical notes, the hospital data base and the pre- and post-treatment study models of 70 patients who were treated with fixed appliances. The pre- and post-treatment models were assessed using the Index of Orthodontic Treatment Need (IOTN) and the Peer Assessment Rating (PAR) index. RESULTS: (1) 98.5% of the patients treated with fixed appliances in both hospitals were in definite need for treatment, (2) The mean percentage PAR score reduction was 81.5%, (3) The mean treatment duration was 27 months with an average of 21 appointments, (4) Factors increasing treatment duration included being a female patient, class I malocclusion, IOTN 5, extractions, prescribing headgear wear, using functional appliances or quadhelixes and increased number of missed appointments, (5) Factors reducing the treatment time were male patients, class II or class III malocclusions and an increased number of emergency appointments. CONCLUSIONS: The hospitals demonstrated a high standard of orthodontic treatment.

An in vitro investigation of pre-treatment effects before fissure sealing.

BACKGROUND: Fissure sealants prevent occlusal caries in permanent molars. Enamel preparation methods are used before fissure sealing. AIMS: To investigate effects of bioglass air-abrasion pre-treatment with and without an adhesive, on fissure enamel of permanent teeth, with respect to etchability, microleakage and microtensile bond strength. DESIGN: Half of the occlusal surfaces of 50 extracted premolars underwent bioglass air-abrasion. Dye was applied to the entire occlusal surface. Photographs were taken to score etched surface by dye uptake. Adhesive was applied to 25 of the bioglass-treated areas and all teeth were fissure sealed, sectioned, and evaluated using confocal microscopy. Buccal and lingual surfaces of a further eight premolars were acid-etched and randomly received: air-abrasion, adhesive, both, or none before sealant application for microtensile bond strength measurement in half of the samples immediately and half following 6 months of water immersion. RESULTS: Linear mixed models and multinomial logistic regression were used (P = 0.05). Bioglass air-abrasion significantly improved enamel etchability and reduced microleakage. The addition of an adhesive made no difference to either microleakage or microtensile bond strength. The combination of bioglass abrasion and adhesive led to more cohesive, rather than adhesive, failure. CONCLUSIONS: Bioglass air-abrasion improved enamel etchability and reduced microleakage irrespective of the adhesive use but neither pre-treatment affected the microtensile bond strength.

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.

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.

YouTube™ as an information resource for orthognathic surgery.

OBJECTIVE: To investigate video content on YouTube™ related to orthognathic surgery. MATERIALS AND METHODS: YouTube™ was searched using the terms: orthognathic surgery; orthodontic surgery; jaw surgery; jaw corrective surgery. Inclusion criteria included English language; primary content orthognathic surgery and acceptable audio-visual quality. Videos were sorted into the top 50 for each search term by view-count and into an overall top 60 from the four searches. The following parameters were recorded for each video: number of views; likes; dislikes; source; primary intention. Each was classified according to information content as 'excellent', 'moderate' or 'poor'. A pre-determined list of orthognathic surgery-related information domains was also evaluated. RESULTS: The top 60 videos had a combined total of 6,986,141 views. Videos predominantly involved patients describing their personal experience (41.67%) with the majority positively biased (61.67%). Only 9.17% of videos were classified as having excellent general information content and 55.83% were rated as poor. Surgical procedures were described in 45% whilst the need for pre- and post-surgical orthodontics was discussed in 33% and 16%, respectively. Post-operative paraesthesia was discussed in 17.5% of videos outcome. CONCLUSIONS: Video content on YouTube™ relating to orthognathic surgery is substandard and patients should be advised to view it with caution.

Relationship between maxillary central incisor proportions and facial proportions.

STATEMENT OF PROBLEM: No universally accepted parameter exists for selecting maxillary central incisors (MCIs) relative to facial proportions. PURPOSE: The purpose of this prospective clinical study was to determine the relationship between MCIs and facial height and width in adults, intersex differences, and measurement differences between right and left MCI. MATERIAL AND METHODS: A prospective study was undertaken of 149 dental students (F:76; M:73) aged between 18 and 30 years. Anthropometric MCI and horizontal and vertical facial measurements were recorded with digital calipers by 1 operator. Correlation was investigated with Pearson correlation coefficients (α=.05). Two-sample t tests were used for intersex comparisons and paired t tests to compare right and left MCIs. Intraexaminer reliability was tested by remeasuring 25 participants and applying the Bland-Altman and Lin analyses. RESULTS: The mean MCI height was 10.28 mm (right and left) and the mean widths were 8.65 mm (right) and 8.66 mm (left). Intersex incisor differences existed for height measurements (M:F 0.54 mm [right], 0.46 mm [left]) and width measurements (M:F 0.26 mm) but not for width-to-height ratios (F=0.85; M=0.84). A mean ratio of 15.56 was found between bizygomatic width:tooth width (M=15.75, F=15.37) and of 17.93 between total face height:MCI height (M=17.97, F=17.89). Correlation coefficients were low for all tooth:face measurements. Intraexaminer reliability was clinically acceptable. CONCLUSIONS: Men had larger teeth and faces but similar width:height ratios. There was no significant size difference between right and left MCI, little individual relationship between tooth:face proportions, and insignificant sex influence. The "biometric ratio"' of 1:16 for MCI:bizygomatic width was not reconfirmed exactly. A ratio of 1:18 is proposed for MCI height to total face height (Tr-Me') and 1:12 for face height (N'-Me').

Development of a 3D printable maxillofacial silicone: Part I. Optimization of polydimethylsiloxane chains and cross-linker concentration.

STATEMENT OF PROBLEM: Conventionally, maxillofacial prostheses are fabricated by hand carving the missing anatomic defect in wax and creating a mold into which pigmented silicone elastomer is placed. Digital technologies such as computer numerical control (CNC) milling and 3-dimensional (3D) printing have been used to prepare molds directly or indirectly into which a biocompatible pigmented silicone elastomer is placed. PURPOSE: The purpose of this in vitro study was to develop a silicone elastomer by varying composition that could eventually be 3D printed directly without a mold to create facial/body prostheses. MATERIAL AND METHODS: The silicone was composed of polydimethylsiloxane (PDMS), filler, catalyst, and cross-linker. Four types of base silicone polymers were prepared with different PDMS molecular weight combinations with long, medium, and short chain length PDMS. The effect of the cross-linker (2.5% to 12.5%) content in these bases was assessed for the effect upon the mechanical properties of the elastomer. Ten readings were made for each formulation, and differences in the means were evaluated with a 2-way ANOVA (α=.05). RESULTS: Variations in silicone composition resulted in hardness from 6.8 to 28.5 durometer, tensile strength from 0.720 to 3.524 kNm-1 and tear strength from 0.954 to 8.484 MPa. Significant differences were observed among all formulations (P<.05). These formulations have mechanical properties comparable with the commercial silicones currently used for the fabrication of facial prostheses. The formulation with 5% cross-linker content and high content of long-chain PDMS chains with optimum mechanical properties was chosen for further development. CONCLUSIONS: The optimum combination of mechanical properties implies the use of one of these formulations for further evaluation in a 3D printer capable of actively mixing and extruding 2-component, room temperature vulcanization silicone.

Does a true knowledge of dental crowding affect orthodontic treatment decisions?

OBJECTIVES: To assess whether a true knowledge of crowding alters treatment decisions compared with estimates of crowding. MATERIALS AND METHODS: Thirty-six orthodontists were asked to estimate crowding using visualization on eight mandibular arch study models and to indicate possible extraction choices. For each model, the intermolar widths, intercanine widths, and clinical scenarios were identical, but the true crowding varied from 0.2 to 8.4mm as to a lesser extent did the curve of Spee. Eleven orthodontists repeated the visualization exercise after 2 weeks to assess reliability. All 36 of the orthodontists were asked to repeat the treatment planning exercise on the same models, but this time was provided with the true amount of crowding in each case. RESULTS: When the 36 orthodontists used direct visualization of the models to assess crowding, the range of their estimates of crowding increased as the crowding increased. As might be expected, they also tended to move towards extraction treatments as the crowding increased (P = 0.013, odds ratio = 3). Although the reliability of the repeat estimates of crowding were moderate, the mean estimates were greater than the true crowding for each model. When orthodontists were presented with the true amount of crowding, rather than their estimate of crowding, it had a significant effect on the decision to extract, with fewer orthodontists recommending extractions. LIMITATIONS: The principal limitation of this study is that it was a laboratory-based study and utilized just the mandibular arch model for estimation and treatment planning. CONCLUSIONS: Direct visualization may overestimate the amount of crowding present. When the true amount of crowding is known, it can lead to more consistent treatment planning, with the decision to extract fewer teeth in the borderline cases. A formal space analysis is likely to assist with treatment planning.