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.

Is visual imagery ability higher for orthodontic students than those in other disciplines? A cross-sectional questionnaire-based study.

OBJECTIVE: To investigate the effect visual imagery may have on career choice among current university students across a range of subjects and disciplines. SETTING: University College London (UCL), UK. DESIGN: Cross-sectional questionnaire-based study. PARTICIPANTS: The study compared four main groups of UCL students: current students at the Slade School of Fine Art; UCL Eastman Dental Institute; UCL Bartlett School of Architecture; and the Faculty of Laws. METHOD: A questionnaire based on the Vividness of Visual Imagery Questionnaire (VVIQ) was distributed along with questions regarding demographic information. RESULTS: There were no significant differences between the VVIQ scores across the four included Schools/Faculty: The Slade School of Fine Art; UCL Bartlett School of Architecture; Faculty of Laws; and UCL Eastman Dental Institute, F(3,219) = 2.160, P = 0.094. There were also no significant differences in the scores for the Eastman (M = 60.21, SD = 13.58) and the three other Schools/Faculty (M = 62.87, SD = 10.96); t(-1.317) = 221, P = 0.189, and no significant difference in the scores for the Orthodontic students (M = 60.80, SD = 13.39) and the remaining other included students (M = 61.44, SD = 9.68); t(-0.232) = 221, P = 0.817. Aphantasia was uncommon in this sample, with a prevalence of 0.9%. A positive correlation was found between age group and total VVIQ score, with older participants scoring higher on the VVIQ. Women were significantly more likely to say that their ability to visualise had affected their career choice than male respondents. CONCLUSIONS: There were no significant differences between the VVIQ scores across the four included Schools/Faculty. Visual imagery ability did not differ in dental or orthodontic students in comparison to other student groups. Further work is needed to replicate these findings in more diverse samples.

Occlusal outcomes in combined orthodontic and orthognathic treatment.

OBJECTIVE: To investigate the treatment outcome in terms of the malocclusion features and the changes in the occlusion of patients undergoing orthodontic/orthognathic treatment using the Peer Assessment Rating (PAR) and the Index of Complexity, Outcome and Need (ICON) and to test the application of the Index of Orthognathic Functional Treatment Need (IOFTN) on this sample as a measure of orthognathic pre-treatment need. DESIGN: Retrospective longitudinal cohort study. SETTING: The orthodontic department at the Eastman Dental Hospital. MATERIAL AND METHODS: The study models of a sample of 100 orthodontic/orthognathic patients who were treated at the Eastman Dental Hospital were measured using the PAR index and ICON at three stages: pre-treatment, pre-surgery and at debond. Treatment need was assessed by measuring IOTN and IOFTN using start study models. RESULTS: 99% of the sample showed an improvement in PAR score, with 82% of the sample being greatly improved. ICON showed that 95% of the sample had an improvement of different degrees with 5% being not improved or worse. The IOFTN qualified 97% of the patients for orthognathic treatment when used retrospectively on the sample while the DHC of IOTN qualified the whole sample for orthodontic treatment. CONCLUSIONS: Orthodontic/orthognathic treatment showed improved and acceptable overall results. The PAR index and ICON were valid measures to investigate the outcome of orthognathic treatment. IOFTN proved to be a useful tool in determining and prioritizing orthognathic treatment based purely on functional need.

Development of a novel smart scaffold for human skeletal muscle regeneration.

Skeletal muscle defects are notoriously difficult to manage and the current methods used are associated with many limitations. Engineered skeletal muscle tissue has the potential to provide a solution that circumvents these disadvantages. Our previous work has identified a novel three-dimensionally aligned degradable phosphate glass fibre scaffold that can support myoblast differentiation and maturation. This current study has further developed the scaffold by encasing the fibres within a collagen gel to produce a smart composite scaffold that provides key biomimetic cues and supports the formation of a tissue that may be implanted in vivo. The constructs formed were approximately 30 mm long and microscopic examination confirmed favourable unidirectional cell alignment. There was good cell survival, and gene expression studies demonstrated upregulation of the myogenic regulatory factors and developmental and adult myosin heavy chain isoforms indicating myofibre formation and maturation respectively. Compared with the three-dimensional glass fibre scaffolds, the composite scaffolds had later gene upregulation, however, the use of collagen gels reinforced with degradable aligned glass fibres offers the opportunity to create a tissue analogue that can be easily manipulated. Furthermore, the glass fibre ends could support tendon/bone formation, and the channels formed as the fibres degrade could allow for vascular ingrowth.

The influence of surface roughness and surface dynamics on the attachment of Methicillin-Resistant Staphylococcus aureus onto orthodontic retainer materials.

Staphylococci species have been isolated from removable orthodontic retainers. The aims of this study were to determine the most suitable device to analyze surface roughness of autopolymerized acrylic and thermoplastic materials and whether the surface dynamics of these materials influences the attachment of Methicillin-Resistant Staphylococcus aureus (MRSA). Clinically simulated samples of autopolymerized acrylic and thermoplastic material were first evaluated using laser non-contact, stylus mechanical profilometries and atomic force microscopy (AFM) followed by contact angle measurement to characterize their surface dynamics. Finally, an in vitro biofilm assay was carried out using a constant depth film fermentor to assess biofilm attachment. The results showed a significant difference between the roughness values obtained from the tested profilometers with the AFM exhibiting the most consistent roughness values. MRSA tended to accumulate initially within the microscopic irregularities of autopolymerized acrylic samples whereas acid-base and electron donor interactions influenced the bacterial attachment onto the thermoplastic samples.

An index of orthognathic functional treatment need (IOFTN).

OBJECTIVE: To design a new index categorizing the functional need for orthognathic treatment. DESIGN: Laboratory-based study. SETTING: Records were obtained from two UK hospital-based orthodontic departments. PARTICIPANTS: A panel of four consultant orthodontists, experienced in providing orthognathic care, devised a new index of Orthognathic Functional Treatment Need (IOFTN) with the aid of the membership of the British Orthodontic Society Consultant Orthodontists Group (COG). Twenty-three consultants and post-CCST level specialists took part in the study as raters to test the validity and reliability of the new index. METHODS: A total of 163 start study models of patients who had previously undergone orthognathic treatment were assessed by the panel of four consultant orthodontists using the new index (IOFTN) and the agreed category was set as the 'gold standard'. Twenty-one consultants and post-CCST level specialists then scored the models on one occasion and two scored 50 sets of models twice to determine the test-re-test reliability. RESULTS: Kappa scores for inter-rater agreement with the expert panel for the major categories (1-5) demonstrated good to very good agreement (kappa: 0·64-0·89) for all raters. The percentage agreement ranged from 68·1 to 92% in all cases. Intra-rater agreement for the major categories was moderate to good (kappa: 0·53-0·80). CONCLUSIONS: A new index, the IOFTN, has been developed to help in the prioritization of severe malocclusions not amenable to orthodontic treatment alone. It demonstrates good content validity and good inter-rater and moderate to good intra-rater reliability. As a result of being an evolution of the IOTN, the familiar format should make it easy to determine functional treatment need within daily orthognathic practice.

Sequential identification of a degradable phosphate glass scaffold for skeletal muscle regeneration.

Tissue engineering has the potential to overcome limitations associated with current management of skeletal muscle defects. This study aimed to sequentially identify a degradable phosphate glass scaffold for the restoration of muscle defects. A series of glass compositions were investigated for the potential to promote bacterial growth. Thereafter, the response of human craniofacial muscle-derived cells was determined. Glass compositions containing Fe4- and 5 mol% did not promote greater Staphylococcus aureus and Staphylococcus epidermidis growth compared to the control (p > 0.05). Following confirmation of myogenicity, further studies assessed the biocompatibility of glasses containing Fe5 mol%. Cells seeded on collagen-coated disks demonstrated comparable cellular metabolic activity to control. Upregulation of genes encoding for myogenic regulatory factors (MRFs) confirmed myofibre formation and there was expression of developmental MYH genes. The use of 3-D aligned fibre scaffolds supported unidirectional cell alignment and upregulation of MRF and developmental MYH genes. Compared to the 2-D disks, there was also expression of MYH2 and MYH7 genes, indicating further myofibre maturation on the 3-D scaffolds and confirming the importance of key biophysical cues.

Molecular changes in detrained & retrained adult jaw muscle.

A hypofunctional masticatory system was developed in 21-day-old male rats by feeding them a soft diet for 27 weeks. Retraining of a parallel group for 6 weeks was achieved by switching back to a hard diet after 21 weeks. A control group was fed a hard diet for 27 weeks. At the end of the experimental period, the expression levels of the myosin heavy chain isoform genes MYH 1 and 2 (fast), 3 (embryonic) and 7 (slow) in the deep masseter were compared using qRT-PCR analysis. The gene expressions of MYH 3 and MYH 7 were significantly higher in the rehabilitation group compared with the normal and hypofunctional group, but no significant differences were found in regards to the gene expression of MYH 1 and 2. Retraining made it possible for the slow (MYH 7) isoform levels to adapt to the increased mechanical load. The increased level of embryonic (MYH 3) isoform could be due to the need of creation of new MYH isoforms.

Accuracy of positioning three types of self-ligating brackets compared with a conventionally ligating bracket.

OBJECTIVES: The aim of this study was to determine whether the morphology of three different self-ligating brackets affects the accuracy of their positioning when compared with a conventionally ligating bracket. DESIGN: An ex vivo prospective comparison of the accuracy of positioning self-ligating brackets with conventionally ligating brackets. SETTING: Orthodontic Department, Eastman Dental Institute, London, UK. SUBJECTS AND METHODS: Twenty-five clinicians with 2 or more years experience of bracket placement bonded four identical typodont malocclusions with Damon MX(TM), In-Ovation System R(TM) and SmartClip(TM) self-ligating brackets and also Victory Series(TM) conventionally ligating brackets. Four hundred brackets of each type were positioned. Vertical, horizontal and angular bracket position errors were assessed by reference to the FA point and FACC respectively, using digital images and image analysis software. RESULTS: Method error analysis showed no evidence of bias and minimal random error. The Victory Series brackets were the most accurately positioned. Although the amount of positioning error for all the self-ligating brackets was small, a greater number were positioned outside vertical and horizontal tolerance limits compared to the conventionally ligated brackets (P<0·001). The Damon MX bracket type was nearly 10 times more likely to be inaccurately placed relative to the FA point compared with the Victory Series bracket. The differences relating to angular positioning error were not statistically significant (P>0·05). CONCLUSION: The findings indicate that the positioning of three types of self-ligating brackets was less accurate than the conventional pre-adjusted edgewise bracket, when using a direct bonding technique. This may have implications for their clinical application.

Effect of occlusal plane on smile attractiveness.

OBJECTIVE: To determine the influence of the occlusal plane angle on smile attractiveness as perceived by a group of adult orthodontic patients and dentists. MATERIALS AND METHODS: The first stage utilized a laboratory approach to record changes in vertical tooth position at different occlusal plane angles using a maxillary model mounted on an articulator. In the second stage, photographic manipulation was undertaken, using data from stage 1, to produce a computerized prediction of the appearance of the smile at differing occlusal plane angles (0, 5, 10, 15, and 20 degrees). Finally, the five developed photographs were assessed by participants. RESULTS: Alterations in the occlusal plane angle did affect relative smile attractiveness for both patients (n  =  66) and dentists (n  =  66). For patients, the 10 degree smile was rated better than the 0 and 20 degree smiles (P < .01); for dentists, the 15 degree smile was rated better than the 0 and 20 degree smiles (P < .01). The 5, 10, and 15 degree smiles were indistinguishable for patients, and the 10 and 15 degree smiles were indistinguishable for dentists. CONCLUSION: Changing the occlusal plane angle does affect relative smile attractiveness. However, patients were more tolerant of these changes than dentists. This suggests that large changes in the occlusal plane angle would affect relative smile attractiveness, and small changes are unlikely to affect smile attractiveness.

Grouping patients for masseter muscle genotype-phenotype studies.

OBJECTIVES: To use various facial classifications, including either/both vertical and horizontal facial criteria, to assess their effects on the interpretation of masseter muscle (MM) gene expression. MATERIALS AND METHODS: Fresh MM biopsies were obtained from 29 patients (age, 16-36 years) with various facial phenotypes. Based on clinical and cephalometric analysis, patients were grouped using three different classifications: (1) basic vertical, (2) basic horizontal, and (3) combined vertical and horizontal. Gene expression levels of the myosin heavy chain genes MYH1, MYH2, MYH3, MYH6, MYH7, and MYH8 were recorded using quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and were related to the various classifications. The significance level for statistical analysis was set at P ≤ .05. RESULTS: Using classification 1, none of the MYH genes were found to be significantly different between long face (LF) patients and the average vertical group. Using classification 2, MYH3, MYH6, and MYH7 genes were found to be significantly upregulated in retrognathic patients compared with prognathic and average horizontal groups. Using classification 3, only the MYH7 gene was found to be significantly upregulated in retrognathic LF compared with prognathic LF, prognathic average vertical faces, and average vertical and horizontal groups. CONCLUSION: The use of basic vertical or basic horizontal facial classifications may not be sufficient for genetics-based studies of facial phenotypes. Prognathic and retrognathic facial phenotypes have different MM gene expressions; therefore, it is not recommended to combine them into one single group, even though they may have a similar vertical facial phenotype.

A new style of orthognathic clinic.

The Orthognathic Team at the Eastman Dental Hospital has developed a new style of multidisciplinary clinic to supplement the traditional orthognathic consultation. The aim of the new clinic is to increase patient satisfaction and involvement in the consent and decision making process, as well as optimizing the information given to prospective patients regarding all aspects of this complex elective treatment. Results of a survey of patients attending the clinic found that 80% thought that the information given was 'just the right amount' and 96% were satisfied with the new structure. They particularly found it useful to meet a patient who had completed treatment. All of those who attended said that they understood the information given to them and would recommend the clinic to those considering orthognathic treatment. They also liked having other patients there with them on the clinic.

A cephalometric study to investigate the skeletal relationships in patients with increasing severity of hypodontia.

OBJECTIVES: To determine the skeletal relationships in patients with hypodontia and analyze the effects of severity and pattern. MATERIALS AND METHODS: Pretreatment lateral cephalograms from 277 patients with hypodontia, categorized by the number of missing teeth as mild (1-2), moderate (3-5), or severe (> or =6), were digitized recording angular measurements and ratios and compared with published norms matched for age and gender. Pattern was determined as mandibular, maxillary, bimaxillary, bilateral, anterior, posterior, and anteroposterior. Linear regression models assessed relationships between number of missing teeth and cephalometric parameters, controlling for the pattern of hypodontia. RESULTS: For every additional missing tooth, SNA, SNB, and ANB decreased 0.3 degrees , 0.1 degrees , and 0.2 degrees , respectively; this was clinically significant for >4, >10, and >5 missing teeth, respectively. Mandibular to cranial base ratio decreased 0.3% for every additional missing tooth; this was clinically significant for >10 missing teeth. The MMPA decreased 0.3 degrees for every additional missing tooth; this was clinically significant for >7 missing teeth. Percentage LAFH decreased 0.2% for every additional missing tooth; this was significant for >7 missing teeth. Jarabak ratio increased 0.2% for each additional missing tooth; this was clinically significant for >10 missing teeth. Anterior hypodontia significantly decreased most cephalometric parameters. CONCLUSIONS: Patients with hypodontia demonstrated a tendency toward a Class III relationship, caused by decreased maxillary and mandibular angular prognathism and MnCB ratio, though the effect was greater on the maxilla than the mandible. Clinical significance was only associated with severe hypodontia. Vertically, there was a tendency toward decreased MMPA and %LAFH; this was clinically relevant only with severe hypodontia. Anterior hypodontia had a significant effect on skeletal relationship.

Myosin proteins identified from masseter muscle using quantitative reverse transcriptase-polymerase chain reaction--a pilot study of the relevance to orthodontics.

There is a clearly established relationship between masticatory muscle structure and facial form. Human studies in this area, however, have been limited, especially in consideration of the myosin heavy chain (MyHC) family of contractile proteins. The aim of this pilot study was to assess if differences were detectable between genotype with respect to MyHC isoforms and the vertical facial phenotype in a sample of nine Caucasian female patients, age range 18-49 years, using a novel rapid technique. Masseter muscle biopsies were taken from patients with a range of vertical facial form. The levels of expression of the MyHC isoform genes MYH 1, 2, 3, 6, 7, and 8 were compared with the expression in a female calibrator patient aged 23 years with normal vertical facial form, using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Statistical analysis was undertaken using Pearson correlation coefficient. The results showed that there were distinct differences in gene expression between patients with a wide range of variation although changes in MYH1 were consistent with one cephalometric variable, the maxillo-mandibular angle. The full procedure, from start to finish, can be completed within half a day. Rapid genotyping of patients in this way could reveal important information of relevance to treatment. This technology has potential as a diagnostic and prognostic aid when considering correction of certain malocclusions.

Alpha v beta 3 and alpha v beta 5 integrins and their role in muscle precursor cell adhesion.

BACKGROUND INFORMATION: Functional adaptation of skeletal muscle is a requirement for different muscle groups (e.g. craniofacial, ocular and limb) to undergo site-specific changes. Such tissue remodelling depends on dynamic interactions between muscle cells and their extracellular matrix, via participation of multifunctional molecules such as integrins. In view of data suggesting a role in fundamental muscle biology and muscle development in other systems, the present study has focused on expression and function of alpha v integrins, in cultured adult human craniofacial muscle (masseter) precursor cells and myotubes, and the predominantly fibroblastic IC (interstitial cells) population. RESULTS AND CONCLUSIONS: Flow-cytometric phenotyping and immunofluorescence phenotyping show that alpha v, alpha v beta 3 and alpha v beta 5 are expressed in all mononuclear cells (muscle precursors and IC) seeded on muscle extracellular molecules such as gelatin, VN (vitronectin) and FN (fibronectin). In this system, blockade of alpha v activity using a function-perturbing antibody abrogates cell migration on VN and FN. alpha v integrins act predominantly as VN receptors as cell-substrate attachment is diminished when alpha v neutralizing agents are introduced into cultures seeded on VN, and this inhibition is reversible; these integrins also appear to be minor FN receptors. These results demonstrate that the alpha v subset of integrins present on both myogenic precursors and IC is an essential cohort of VN and, to a lesser extent, FN receptors mediating cell adhesion and, either directly or indirectly, arbiters of cell motility.

Dentists' attitudes and practices toward provision of orthodontic treatment for children with visual and hearing impairments.

The objective of this study was to determine differences in behavior and attitudes of dentists in Riyadh, Saudi Arabia, in providing orthodontic care for children who are sensory impaired. A self-administered questionnaire was sent to all dentists working in Riyadh to assess the following domains: personal characteristics of the dentists and their practices, provision of dental care for children who are visually-impaired (Vl) and/or hearing-impaired (HI), and their attitude toward providing orthodontic care for these children. Attitudes were measured on two scales and the overall score of these two scales represented each respondent's attitude. Thirty percent of the dentists provided dental care for children with VI and 45.3 percent did for children with HI. The provision of orthodontic care was significantly affected by the country in which the dentists had received their dental training, both for children with VI and HI (p < 0.01), and by number of years they had been in practice for children with VI (p < 0.05). Regression analysis showed that only the country of dental training significantly affected the dentist's attitude score. There were also significant variations in attitudes toward the provision of orthodontic treatment for children with sensory impairment (SI), influenced by dental training and experience. In practical terms, this means that improvement in attitudes needs to be initiated at the dental undergraduate level. Establishing global guidelines for the provision of orthodontic treatment for patients with sensory impairment is likely to assist both professionals and patients.

A three-dimensional in vitro model system to study the adaptation of craniofacial skeletal muscle following mechanostimulation.

The aim of this study was to investigate the in vitro response of human craniofacial muscle-derived myotubes (primitive/nascent muscle fibres), in three-dimensional constructs, to strain in vitro to mimic clinical scenarios, using expression of the mechanoresponsive gene gelatinase-A/matrix metalloproteinase-2 (MMP-2) as a marker of remodelling of muscle extracellular matrix. Three-dimensional (3D) constructs of cells derived from explants of human masseter muscle (human craniofacial muscle-derived cells; hCMDC) in collagen sponges were subjected to mechanical, uniaxial strain using the Bio-Stretch system. 3D myotube constructs were exposed to the strain regimes of rapid ramp stretch (RRS) or cyclical ramp strain (CRS) with 7.5% and 15% strain. The activity of MMP-2 was assessed by zymography of construct-conditioned medium, whilst lysates of the constructs were used to measure creatine phosphokinase (CPK) activity to confirm the presence of myotubes in the strained constructs. Scanning electron microscopy of the collagen sponges and the CPK assays confirmed the presence of myotubes. MMP-2 was expressed by all the samples and controls, but expression was found to be significantly higher in those cultures strained continuously (RRS), compared to cyclical strain (CRS), and in those strained at 15% compared to 7.5%. Thus, MMP-2 expression, and hence extracellular matrix remodelling, is up-regulated in response to strain and is dependent upon the amount and type of strain to which the muscle is subjected.

Human adult craniofacial muscle-derived cells: neural-cell adhesion-molecule (NCAM; CD56)-expressing cells appear to contain multipotential stem cells.

Skeletal muscle has been well characterized as a reservoir of myogenic precursors or satellite cells with the potential to participate in cellular repopulation therapies for muscle dysfunction. Recent evidence, however, suggests that the postnatal muscle compartment can be considered an alternative to bone marrow as a source of multipotent cells or muscle-derived stem cells (MDSCs). MDSCs, when primed with appropriate environmental cues, can differentiate into a variety of non-muscle cells. The present study describes the application of a new technique for the isolation of adult human myoblasts and putative MDSCs, based on microbead-immunomagnetic selection of CD56+ cells, derived from craniofacial skeletal muscle, and details changes in morphological/molecular phenotype of the purified cells when maintained in either a myogenic or a non-myogenic milieu. Multiple immunofluorescence microscopy and two-colour flow-cytometric analysis of proliferating CD56+ cultures revealed positive staining for myogenic markers (CD56, desmin and M-cadherin) as well as putative stem-cell markers [the antigens CD34, CD90 and CD106, and Flk-1 (fetal liver kinase-1)/VEGFR-2 (vascular-endothelial-growth-factor receptor)]. Confluent cultures subjected to cycles of adipogenic or osteogenic induction contained either adipocytes or osteoblasts and myotubes. In conclusion, the CD56+ subpopulation within adult human skeletal muscle is heterogeneous and is composed of both lineage-committed myogenic cells and multipotent cells (the candidate MDSCs), which are able to form non-muscle tissue such as fat and bone.

The views and attitudes of parents of children with a sensory impairment towards orthodontic care.

A questionnaire was sent to the parents of 77 visually impaired (VI), 210 hearing impaired (HI) and 494 control children seeking their views on their child's dental appearance, orthodontic treatment need and issues that might influence the child undertaking treatment. The parents' views were compared with a dentist's assessment of treatment need using the Index of Orthodontic Treatment Need (IOTN). There was disagreement between the dentist's assessment and the parents' perceptions in all groups. However, the least disagreement was seen in the HI group. There was a statistically significant (P < 0.05) association between control and HI parents' views of their children's treatment needs and their opinion on their dental appearance. Most parents thought that orthodontic treatment was difficult to obtain and expensive and that their child would find difficulty coping with the treatment. Furthermore, parents of VI children considered that treatment was unlikely to be undertaken due to their child's reduced concern for their appearance. The study indicates that the awareness of treatment need for VI and HI children differs between their parents and dentists.

The relationship between maxillary length, differential maxillary impaction, and the change in maxillary incisor inclination.

A mathematical formula based on a geometric model is described that will permit greater accuracy in planning orthodontic treatment and orthognathic surgery for patients who require differential maxillary impaction.