The influence of miniscrew insertion torque.

Objective: The aim of this in vitro study was to evaluate the progressive development of surface microdamage produced following the insertion of orthodontic miniscrews (OMs) into 1.5 mm thick porcine tibia bone using maximum insertion torque values of 12 Ncm, 18 Ncm, and 24 Ncm. Methods: Aarhus OMs (diameter 1.5 mm; length 6 mm) were inserted into 1.5 mm porcine bone using a torque limiting hand screwdriver set at 12 Ncm, 18 Ncm, and 24 Ncm. A custom rig equipped with a compression load cell was used to record the compression force exerted during manual insertion. A sequential staining technique was used to identify microdamage viewed under laser confocal microscopy. Virtual slices were created and stitched together to form a compressed two-dimensional composition of the microdamage. Histomorphometric parameters, including total damage area, diffuse damage area, maximum crack length, maximum damage radius, and maximum diffuse damage radius, were measured. Kruskal-Wallis Tests and Wilcoxon Rank-Sum Tests were used to analyse the generated data. Results: All OMs inserted using 12 Ncm failed to insert completely, while partial insertion was observed for two OMs inserted at 18 Ncm. Complete insertion was achieved for all OMs inserted at 24 Ncm. Histomorphometrically, OMs inserted using 24 Ncm produced a significantly larger diffuse damage area (P < 0.05; P < 0.05) and maximum diffuse damage radius (P < 0.05; P < 0.05), for both the entry and exit surfaces, respectively, compared with the 12 Ncm and 18 Ncm groups. Conclusions: Insertion torque can influence the degree of OM insertion and, subsequently, the amount of microdamage formed following insertion into 1.5 mm thick porcine tibia bone. An increase in insertion torque corresponds with greater insertion depth and larger amounts of microdamage.

Influence of cortical bone thickness on miniscrew microcrack formation.

INTRODUCTION: The aim of this in-vitro study was to investigate the influence of cortical bone thickness on the amount of surface microdamage produced after insertion of orthodontic miniscrews (OM) in porcine tibia bone. METHODS: Aarhus OMs (Medicon, Tuttlingen, Germany; diameter, 1.5 mm; length, 6 mm) were inserted into 1.0 mm (group A; n = 10), 1.5 mm (group B; n = 10), and 2.0 mm (group C; n = 10) of porcine cortical bone using a torque-limiting hand screwdriver set at 18 Ncm. A sequential staining technique was used to identify microdamage under laser confocal microscopy. Virtual slices were stitched together using ImageJ software (National Institutes of Health, Bethesda, Md) to form a compressed 2-dimensional composition of the microdamage. The ImageJ software was used to quantify the total damage area, diffuse damage area, maximum crack length, maximum damage radius, and maximum diffuse damage radius. Kruskal-Wallis tests and Wilcoxon rank sum tests were used to analyze the data. RESULTS: All OMs in group A (1.0 mm) were inserted completely; however, 2 OMs from group B (1.5 mm) and all OMs in group C (2.0 mm) failed to insert completely. The entry surface of group C (2.0 mm) exhibited significantly higher amounts of total damage, diffuse damage area, maximum crack length, and maximum crack damage radius compared with groups A (1.0 mm) and B (1.5 mm). The maximum crack length observed on the entry and exit surfaces ranged from 1.03 to 3.06 mm. CONCLUSIONS: In this study, we demonstrated a higher level of microdamage after the insertion of OMs into 2.0-mm thick cortical bone compared with 1.0-mm thick cortical bone. Therefore, clinicians need to consider the thickness of the cortical bone at the insertion site, because mechanisms to reduce cortical bone thickness would likely reduce the amount of microdamage formed. A safety zone of 3.5 mm from the OM is also recommended for OMs inserted into 1.0- and 1.5-mm cortical bone thicknesses to minimize any detrimental effects after targeted remodeling.

Qualitative evaluation of pretreatment patient concerns in orthodontics.

INTRODUCTION: A discrepancy exists between objective and subjective measures of orthodontic treatment need, highlighting the importance of patients' perceptions. Limited qualitative information is available regarding patients' perceptions and orthodontic concerns. For the first time, patient facial images and qualitative methodology were used to assess patients' orthodontic concerns, which are incorporated into and are important in treatment planning and consent. METHODS: An interview-based, cross-sectional study of adolescent patients eligible to receive orthodontic treatment in a public dental hospital was conducted with 105 adolescents (42 boys, 63 girls) aged between 12 and 17 years. Each patient's face was video recorded, and 3 images were selected from each recording to assess the patient's orthodontic concerns. The initial chief concerns were compared with concerns articulated after the patients assessed their facial images. In addition, patient concerns were compared with occlusal features visible on smiling using the Dental Aesthetic Index and patient study casts. RESULTS: For 37% of the adolescent patients, smiling images helped to identify additional concerns. For 87%, their smiling images helped them to describe their concerns in more detail. In addition, a few patients did not articulate any concern about features measurable on the Dental Aesthetic Index that were visible on smiling. CONCLUSIONS: Showing adolescent patients images of their face and smile helped them to identify and better describe their concerns. Adolescents are not always overly concerned about visible and quantifiable malocclusion features. This might influence orthodontic treatment planning and consent.

The psycho-social impact of malocclusions and treatment expectations of adolescent orthodontic patients.

OBJECTIVES: To evaluate the short- and long-term orthodontic treatment (OT) expectations, malocclusion severity, and oral health-related quality of life (OHRQoL) status of adolescent patients using qualitative and quantitative methodology. MATERIALS AND METHODS: Adolescents (n = 105; 42 males and 63 females) aged between 12 and 17 years participated in this interview and questionnaire-based study. The Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) and the Oral Impacts on Daily Performances (OIDP) scale evaluated OHRQoL status. Study casts were analysed using the Dental Aesthetics Index (DAI) and the Index of Complexity, Outcome and Need (ICON). Mann-Whitney test and Spearman's correlations tested various univariate variables. RESULTS: With similar index-determined OT need (DAI, P = 0.371 and ICON, P = 0.932) females tended to have worse OHRQoL status (PIDAQ scores, P-values ranged from 0.006 to 0.0001 and scores for the OIDP question related to smiling, laughing, and showing teeth without embarrassment, P-value = 0.015). Occlusal index scores did not have statistically significant associations with the OHRQoL scales. Better dental appearance was expected by 85 per cent of the adolescents in the short-term and by 51 per cent in the long-term after OT. The associated psycho-social expectations were: 1. improved dental self-confidence, 2. positive psychological impact/improved self-worth, and 3. positive social impact. CONCLUSIONS: Female adolescent patients tended to experience worse psycho-social impacts related to their malocclusions compared with males with similar index-determined OT need. Index-determined OT need scores did not correlate with the OHRQoL scales. Adolescent patients expected OT to improve their dental appearance and QoL aspects.

Craniofacial and upper airway morphology in pediatric sleep-disordered breathing and changes in quality of life with rapid maxillary expansion.

INTRODUCTION: The association between pediatric sleep-disordered breathing caused by upper airway obstruction and craniofacial morphology is poorly understood and contradictory. The aims of this study were to evaluate the prevalence of children at risk for sleep-disordered breathing, as identified in an orthodontic setting by validated screening questionnaires, and to examine associations with their craniofacial and upper airway morphologies. A further aim was to assess the change in quality of life related to sleep-disordered breathing for affected children undergoing rapid maxillary expansion to correct a palatal crossbite or widen a narrow maxilla. METHODS: A prospective case-control study with children between 8 and 17 years of age (n = 81) at an orthodontic clinic was undertaken. The subjects were grouped as high risk or low risk for sleep-disordered breathing based on the scores from a validated 22-item Pediatric Sleep Questionnaire and the Obstructive Sleep Apnea-18 Quality of Life Questionnaire. Variables pertaining to a screening clinical examination, cephalometric assessment, and dental cast analysis were tested for differences between the 2 groups at baseline. Ten children who underwent rapid maxillary expansion were followed longitudinally until removal of the appliance approximately 9 months later with a repeated Obstructive Sleep Apnea-18 Quality of Life Questionnaire. All data were collected blinded to the questionnaire results. RESULTS: The frequency of palatal crossbite involving at least 3 teeth was significantly higher in the high-risk group at 68.2%, compared with the low-risk group at 23.2% (P <0.0001). Average quality of life scores in the high-risk group indicated reduced quality of life related to sleep-disordered breathing by 16% compared with children in the low-risk group at baseline (P <0.0001). Cephalometrically, mean inferior airway space, posterior nasal spine to adenoidal mass distance, and adenoidal mass to soft palate distance were reduced in the high-risk group compared with the low-risk group by 1.87 mm (P <0.03), 2.82 mm (P <0.04), and 2.13 mm (P <0.03), respectively. The mean maxillary intercanine, maxillary interfirst premolar, maxillary interfirst molar, mandibular intercanine, and mandibular interfirst premolar widths were reduced in the high-risk group compared with the low-risk group by 4.22 mm (P <0.0001), 3.92 mm (P <0.0001), 4.24 mm (P <0.0001), 1.50 mm (P <0.01), and 1.84 mm (P <0.01), respectively. Children treated with rapid maxillary expansion showed an average improvement of 14% in quality of life scores in the high-risk group compared with the low-risk group, which showed a slight worsening in quality of life related to sleep-disordered breathing by an average of 1% (P <0.04), normalizing the quality of life scores in the high-risk children to the baseline scores compared with the low-risk group. CONCLUSIONS: Children at high risk for sleep-disordered breathing are characterized by reduced quality of life, reduced nasopharyngeal and oropharyngeal sagittal dimensions, palatal crossbite, and reduced dentoalveolar transverse widths in the maxillary and mandibular arches. No sagittal or vertical craniofacial skeletal cephalometric predictors were identified for children at high risk for sleep-disordered breathing. In the short term, rapid maxillary expansion might aid in improvement of the quality of life for children with a narrow maxilla in the milder end of the sleep-disordered breathing spectrum.

Craniofacial and upper airway morphology in pediatric sleep-disordered breathing: Systematic review and meta-analysis.

INTRODUCTION: Pediatric sleep-disordered breathing is a continuum, with primary snoring at one end, and complete upper airway obstruction, hypoxemia, and obstructive hypoventilation at the other. The latter gives rise to obstructive sleep apnea. An important predisposing factor in the development and progression of pediatric sleep-disordered breathing might be craniofacial disharmony. The purpose of this systematic review and meta-analysis was to elucidate the association between craniofacial disharmony and pediatric sleep-disordered breathing. METHODS: Citations to potentially relevant published trials were located by searching PubMed, Embase, Scopus, and the Cochrane Central Register of Controlled Trials. The MetaRegister of controlled trials database was also searched to identify potentially relevant unpublished trials. Additionally, hand-searching, Google Scholar searches, and contact with experts in the area were undertaken to identify potentially relevant published and unpublished studies. Inclusion criteria were (1) randomized controlled trials, case-control trials, or cohort studies with controls; (2) studies in nonsyndromic children 0 to 18 years of age with a diagnosis of sleep-disordered breathing or obstructive sleep apnea by either a sleep disorders unit, screening questionnaire, or polysomnography; and (3) principal outcome measures of craniofacial or upper airway dimensions or proportions with various modalities of imaging for the craniofacial and neck regions. The quality of the studies selected was evaluated by assessing their methodologies. Treatment effects were combined by meta-analysis with the random-effects method. RESULTS: Children with obstructive sleep apnea and primary snoring show increased weighted mean differences in the ANB angle of 1.64° (P <0.0001) and 1.54° (P <0.00001), respectively, compared with the controls. An increased ANB angle was primarily due to a decreased SNB angle in children with primary snoring by 1.4° (P = 0.02). Children with obstructive sleep apnea had a distance from the posterior nasal spine to the nearest adenoid tissue measured along the PNS-basion line reduced by 4.17 mm (weighted mean difference) (P <0.00001) and a distance from the posterior nasal spine to the nearest adenoid tissue measured along the line perpendicular to the sella-basion line reduced by 3.12 mm (weighted mean difference) (P <0.0001) compared with the controls. CONCLUSIONS: There is statistical support for an association between craniofacial disharmony and pediatric sleep-disordered breathing. However, an increased ANB angle of less than 2° in children with obstructive sleep apnea and primary snoring, compared with the controls, could be regarded as having marginal clinical significance. Therefore, evidence for a direct causal relationship between craniofacial structure and pediatric sleep-disordered breathing is unsupported by this meta-analysis. There is strong support for reduced upper airway width in children with obstructive sleep apnea. Larger well-controlled trials are required to address the relationship of craniofacial and upper airway morphology to pediatric sleep-disordered breathing in all 3 dimensions.

Masseter length determines muscle spindle reflex excitability during jaw-closing movements.

INTRODUCTION: The masticatory muscles are considered to be important determinants of facial form, but little is known of the muscle spindle reflex characteristics and their relationship, if any, to face height. The aim of this study was to determine whether spindle reflexes, evoked by mechanical stimulation of an incisor and recorded on the masseter muscle, correlated with different facial patterns. METHODS: Twenty-eight adult volunteers (16 women; ages, 19-38 years) underwent 2-N tap stimuli to their maxillary left central incisor during simulated mastication. Reflexes were recorded during local anesthesia of the stimulated tooth to eliminate the contribution from periodontal mechanoreceptors. Surface electromyograms of the reflex responses of the jaw muscles to these taps were recorded via bipolar electrodes on the masseter muscle and interpreted by using spike-triggered averaging of the surface electromyograms. Lateral cephalometric analysis was carried out with software (version 10.5, Dolphin, Los Angeles, Calif; and Mona Lisa, Canberra, Australia). RESULTS: Two-newton tooth taps produced principally excitatory reflex responses beginning at 17 ms poststimulus. Correlation analysis showed a significant relationship between these muscle spindle reflexes and facial heights: specifically, shorter face heights were associated with stronger spindle reflexes. This correlation was strongest between the derived measure of masseter length and the spindle reflex strength during jaw closure (r = -0.49, P = 0.008). CONCLUSIONS: These results suggest that a similar muscle spindle stimulus will generate a stronger reflex activation in the jaw muscles of patients with shorter faces compared with those with longer faces. This finding might help to explain the higher incidence of clenching or bruxism in those with short faces and also might, in the future, influence the design of orthodontic appliances and dental prostheses.

Immunohistochemical detection of nerve growth factor and its receptors in the rat periodontal ligament during tooth movement.

OBJECTIVES: Nerve growth factor (NGF) and its receptors, p75 and tyrosine receptor kinase A (Trk A), have been shown to increase following trauma. The aims of this study were to examine changes in the detection of NGF and its receptors during orthodontic tooth movement in the rat, and the effects of anti-NGF on these changes. DESIGN: Orthodontic separators were placed between the right maxillary first and second molars of Sprague-Dawley rats which were equally divided into two groups. Animals from the second group were injected with anti-NGF. The left sides served as controls, and animals were sacrificed at 0, 3, 7 and 14 days. RESULTS: Results of immunohistochemical localisation for p75, Trk A, calcitonin gene-related peptide (CGRP) and NGF showed staining intensity increased at day 3, with a peak at day 7 and decreasing intensity at day 14. Anti-NGF injected animals showed reduced staining at all observation periods. CONCLUSION: Data suggest that orthodontic injury induces NGF production, leading to sprouting and invasion by CGRP-positive nerve fibers and that injection of anti-NGF reduces NGF tissue levels and prevents innervation by CGRP-positive fibers.

An evaluation of maxillary and mandibular rotational responses with the Clark twin block appliance.

AIMS: To evaluate the dentofacial changes and growth rotational responses of Angle Class II division 1 patients treated with the Clark twin block functional appliance. METHOD: This retrospective study comprised 13 boys (8.77 +/- 0.86 years) and 13 girls (8.75 +/- 0.70 years) treated by one orthodontist with the Clark twin block appliance. Selection was not biased by outcome and sample size power estimates exceeded 90 per cent. Tracings made on the pretreatment (T1), post-treatment (T2) and observation (T3) radiographs were superimposed on anatomically stable landmarks and the dentofacial changes and growth rotational responses compared. The data were tested for normal distribution and sexual dimorphism. Pearson correlation analyses of the treatment and observation phases were performed. RESULTS: In light of the few sex differences and lack of any consistent trends, the data for the boys and girls were combined. Treatment reduced the overbite, overjet and achieved Class II correction through combinations of maxillary incisor uprighting (U1-SN: -5.3 +/- 5.30), lower incisor proclination (L1-MP: 6.6 +/- 6.80), facial height increase (AFH: 5.1 +/- 4.6 mm), ramal lengthening (Co-Go: 3.3 +/- 2.4 mm) and mandibular length increase (Co-Pog: 5.9 +/- 4.6 mm). During the observation period, similar growth changes were recorded, but the overbite (2.9 +/- 1.9 mm) and overjet (3.6 +/- 2.0 mm) increased due to some reversal of the treatment-induced incisor angulation changes. Over the treatment period (T1 to T2), the angles between the cranial base and maxillary (maxillary rotation) and mandibular stable structures (mandibular internal rotation) reduced by -0.1 +/- 1.2 degrees and -0.3 +/- 2.5 degrees, respectively. The angles between mandibular stable structures and Go-Me (mandibular external rotation) and SN-GoMe (mandibular total rotation) increased by 0.6 +/- 1.7 degrees and 0.9 +/- 2.1 degrees, respectively. Between T2 and T3, maxillary rotation, mandibular internal rotation and total mandibular rotation reduced -1.4 +/- 2.0 degrees, -2.4 +/- 2.5 degrees and -0.7 +/- 1.7 degrees, respectively. Mandibular external rotation increased -1.8 +/- 2.0 degrees. Mandibular total and internal rotation angles were significantly (p < 0.5) reduced at T2, but there were no significant associations between the rotations and dentofacial parameters during or following treatment. CONCLUSIONS: On average, the maxillary and mandibular internal rotations were near zero during treatment, but the small and individually variable changes were not clearly associated with the Class II correction.

An evaluation of head position and craniofacial reference line variation.

Natural head position (NHP) is the usual, balanced position of the head which is adopted for viewing the horizon or an object at eye level. Determination of NHP is useful when reconstructing facial form in art, forensics, orthodontic diagnosis and treatment planning for surgical management of craniofacial dysmorphic conditions. When NHP is uncertain, correction such as orientation to Frankfurt horizontal (FH) has been advocated. However, FH angulation varies between individuals and is subject to landmark identification error. Previous studies have measured FH and other craniofacial planes in relation to the true horizontal (HOR) with subjects in NHP and have found similar variation to that found with FH. This study measured craniofacial planes in 40 Aboriginal Australians (20 male, 20 female, aged 17 years or greater) from lateral cephalographs and compared its results with classical previous studies. Four planes, the neutral horizontal axis (NHA), FH, Krogman-Walker line (KW line), and palatal plane (P plane) demonstrated near parallelism and averaged between -1 degrees and -2 degrees from HOR. The combined use of NHA, FH, KW line, and P plane enables more effective corrected head position (CHP).

Craniofacial reference plane variation and natural head position.

Commonly used craniofacial reference planes such as Frankfort Horizontal (FH) and sella-nasion have shortcomings, including their variable interindividual orientation when related to true horizontal (HOR). Therefore, the aim of this study was to evaluate the potential usefulness of a range of craniofacial reference planes to HOR, including those which have not been investigated previously: the Krogman-Walker (KW) line, the neutral horizontal axis, the foramen magnum line, and the posterior maxillary plane. A sample of 57 (38 female, 19 males) consecutive, pre-treatment orthodontic subjects aged 12-18 years were photographically recorded in a standing mirror-guided natural head position (NHP). Cephalograms taken at the same time were traced, orientated to a plumb line (true vertical) transferred from the photograph, and measured. Descriptive statistical analysis including means and standard deviations (SDs) were used to describe average orientation and variability. Thirty-nine of these subjects were photographically recorded 2 months later to test the reproducibility of NHP. The results showed that the variability of the 11 selected craniofacial reference planes related to HOR was generally high. The planes illustrating the lowest variability to HOR were FH and the KW line with SDs of 4.6 and 4.7 degrees, respectively. These, however, showed approximately double the variation in NHP reproducibility (mean square error 2.1 degree). The KW line and palatal plane were also on average orientated closest to HOR. Therefore, the KW line and palatal plane are potential substitutes for the commonly used reference planes in the absence of a reliable NHP. However, NHP still represents a more valid craniofacial reference system than the investigated reference planes.

Orthodontic practices in Australasia: practice activity.

OBJECTIVE: To collect baseline data on practice types and services provided by orthodontists in Australia and New Zealand. METHOD: A total of 510 questionnaires was sent and 258 were returned. The response rate was 53 per cent. RESULTS: The average age of respondents was 50 years (SD: 9.8 years) with female orthodontists being younger (Mean: 42.3 years; SD: 6.5). The ratio of responding female to male orthodontists was 1:8.8. Overall, more orthodontists were in solo private practice than associateships or partnerships. New Zealand orthodontists were more likely to be in associateships. Australian orthodontists had twice the number of practices (Mean: 2.4; SD: 1.4) than their New Zealand counterparts (Mean: 1.1; SD: 0.3). Orthodontists estimated they saw a mean of 21.3 (SD: 11.3) patients per day. Older orthodontists saw few patients in a day and spent fewer hours in any practice activity in a week. The mean waiting time for a consultation appointment in the private sector in New Zealand was nearly twice that in Australia. There was a significant association between male orthodontists and referral of patients by general dental practitioners. More than three quarters of respondents incorporated retention fees into the treatment fee. Overall, orthodontists were satisfied with the workload and did not want more orthodontists in their geographical area. CONCLUSION: This study provides a sound basis for consideration of challenges in practice and changes over time.

Distribution of the epithelial rests of Malassez and their relationship to blood vessels of the periodontal ligament during rat tooth development.

BACKGROUND: There is some evidence that the epithelial cell rests of Malassez partition the root surface from the periodontal ligament blood vessels, and may protect the root from resorption. OBJECTIVE: The aim of the present study was to determine the distributions of the epithelial rests of Malassez (ERM) and blood vessels in the periodontal ligament (PDL) of the developing rat first molar before, during and after emergence. METHODS: Four Sprague-Dawley rats were sacrificed at two days, one week, two weeks, three weeks, four weeks and six weeks of age. After processing, the maxillae were embedded in paraffin, and sectioned longitudinally and transversely. The sections were stained with a double immuno-histochemical technique which utilised a keratin antibody AE1-AE3 (1:2,000) and an endothelial antibody Factor VIII (1:10,000) to enable simultaneous labelling of ERM and blood vessels. ERM and blood vessel counts were obtained from the mesio-buccal roots of three week, four week and six week-old rats, whilst qualitative observations were made for the earlier developmental stages. RESULTS: ERM cells and cell clusters were found in the tooth third of the PDL width at the three, four and six week stages. Cells and cell clusters increased in number with age, especially in the upper third of the mesio-buccal root. The largest numbers of cells and clusters were found on the distal surfaces of the roots in all age groups. Cells and clusters in all root surfaces increased from three to four weeks, but decreased from four to six weeks. The greatest number of blood vessels was found in the bone-side third of the PDL. The distal surface had the highest proportion of blood vessels, and the palatal surface the least proportion. The number of blood vessels in all surface quadrants did not vary much from three to four weeks of age, but increased from four to six weeks of age, possibly as a reaction to tooth emergence and occlusal function. Physiological root resorption was only observed after tooth emergence, and appeared to be related to loss of continuity of the ERM network and the incursion of blood vessels. CONCLUSIONS: Orthodontic root resorption can be regarded as an exaggerated response to loss of PDL homeostatic control, possibly mediated by the epithelial rests of Malassez.

Syndecan-1 expression during postnatal tooth and oral mucosa development in rats aged from two days to six weeks.

Syndecans are a family of heparan sulphate proteoglycans that regulate cell-matrix interactions that influence cell growth, proliferation and morphology. The aim of this study was to observe changes in the expression of Syndecan-1 in the developing epithelium of the rat oral mucosa and in the epithelial cell rests of Malassez in the developing periodontium of normal rat molars, from late crown development through to early eruption. Immuno-histochemistry (Syndecan-1 N-18) and histochemistry (Alcec Bluel were used to observe changes in the expression of Syndecon-1 in rats aged two to 42 days. Results indicated that during normal tooth development in the rat, labelling or staining of variable intensity for Syndecan-1 was demonstrated in the stratified oral epithelium above the stratum basale in the rat tongue and palate, and in ameloblasts of the developing molar in rats aged two to 14 days. Histochemical staining of the predentine and dentine layers was consistent in all specimens. Labelling or staining for Syndecan-1 was negative in the rat periodontal ligament, which may suggest that either Syndecan-1 was not expressed during normal molar root development or that continued work is required for identification of a suitable label in rats.

The extraction of permanent second molars and its effect on the dentofacial complex of patients treated with the Tip-Edge appliance.

The aim of this investigation was to assess the dentofacial changes in a group of patients consecutively treated with Tip-Edge appliances and the extraction of four permanent second molars by one specialist orthodontic practitioner. Before and after treatment lateral cephalograms and study cast measurements of 45 individuals, 26 females (mean age 13.8 years) and 19 males (mean age 13.9 years), were collated and statistically analysed. Cephalometric variables that exhibited, before treatment, significant sex differences, included SNA, SNB (both smaller in males, P < 0.05) and U1-NA degrees (P < 0.05), nasolabial angle (P < 0.05), and upper lip length P < 0.01 (all larger in males). After treatment, sex differences were demonstrated for SNA (smaller in males, P < 0.05), mandibular length (P < 0.01), upper face height (P < 0.05), lower face height (P < 0.01), anterior face height (P < 0.001), posterior face height (P < 0.01), nasolabial angle (P < 0.05), and upper lip length and thickness (P < 0.001; all larger in males). For the cast analysis, before treatment differences indicated larger values for males than females for lower arch inter-canine, premolar, and molar widths, arch depth (all P < 0.05), tooth size, and arch length (P < 0.01). Similar findings were noted in the upper arch except for inter-canine and premolar arch width. Despite most arch variables displaying sex differences, no gender effect was found for irregularity or crowding parameters. The same variables exhibited significant sex differences and changes after treatment (except tooth size, lower arch depth, and upper arch inter-canine width). Overall, the pattern of correction exhibited by the subjects included dental, skeletal, and soft tissue changes. Males tended to have greater mean increases in mandibular skeletal and soft tissue variables compared with females. Both males and females had increases in most dental arch variables measured from the study casts. Both sexes demonstrated a small uprighting, but statistically non-significant distalizing of the buccal segments. The lower incisors in the sagittal plane revealed a mean tendency to remain in their pre-treatment positions, with some individual variation. Overall, the treatment results were considered favourable, but case selection appeared to bias towards Angle Class I skeletal patterns of average to slightly reduced facial height, overbite and overjet < or = 4 mm, lip competence, no incisor protrusion, and moderate tooth size to arch length discrepancy (3-3.5 mm lower arch, 1 mm upper arch). Further evaluation of third molar eruption responses may provide insight into appropriate timing of second molar extractions.