The right upper first molars of 25 twelve-week-old male Wistar anaesthetized rats were loaded with forces in order to be moved mesially. Constant forces for 4 hours of 0.25 and 0.5 N were applied in five animals each. Furthermore, constant forces for 2 hours of 0.1 N were applied in 10 animals and afterwards, the first and second molars were permanently separated with composite. In these animals, the antagonists were sliced and five rats were killed after 1 day and five after 2 days. As a last experiment, intermittent forces of 0.1 N and 0.25 Hz were applied in five different animals for 4 hours. The untreated contralateral sides served as the control. Paraffin-embedded sections were analysed by immunohistochemistry for proliferating cell nuclear antigen (PCNA), runt-related transcription factor 2 (Runx2/Cbfa1), and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2). Statistical analysis to determine differences between the groups was carried out using a Student's t-test.

In selected areas under tension, the proportion of pERK1/2-positive cells was increased compared with those in control teeth under all types of loading, whereas these proportions in selected areas under pressure were increased only after the application of intermittent forces. In representative areas, both under tension and pressure, the proportion of Runx2-positive cells decreased after the application of constant forces. After the application of constant forces for 4 hours in representative areas, both under tension and pressure, the proportion of PCNA-positive cells was lower than those in control teeth.

The involvement of pERK1/2, Runx2/cbfa-1, and PCNA in the reaction of PDL cells to different load regimens was verified.

A nickel-titanium (Ni-Ti) closed coil spring delivering a force of 10 g was inserted between the upper anterior alveolar bone and the first molar in 8-week-old male C57BL/6 mice. Bisphosphonate (2 µg/20 µl) was injected daily into a local site adjacent to the upper molar. After 12 days, the distance the tooth had moved was measured. The number of tartrate-resistant acid phosphatase (TRAP)-positive cells was counted as osteoclasts in histological sections. Root resorption was assessed by scanning electron microscopy. The data were analysed with a Student's t-test.

The orthodontic appliance increased the number of osteoclasts on the pressure side and mesial movement of the first molar. Bisphosphonates reduced the amount of tooth movement and the number of osteoclasts. In addition, they also reduced root resorption on the pressure side.

Bisphosphonates inhibit orthodontic tooth movement and prevent root resorption during orthodontic tooth movement in mice. These results suggest that bisphosphonates might have an inhibiting effect on root resorption during orthodontic tooth movement in humans and that they may interrupt tooth movement in orthodontic patients undergoing treatment, thus altering the outcome of treatment.

The dental casts and lateral cephalometric radiographs of 301 Croatian subjects (127 males and 174 females, mean age 16.86 ± 2.93 years) were selected from a larger sample of records of the archives of the Orthodontic Department, School of Dental Medicine, University of Zagreb, Croatia. The subjects were from malocclusion groups according to Angle classification, with the corresponding skeletal characteristics. The MD dimensions of all teeth from first molar to first molar were measured on the dental casts using digital callipers. Statistical analysis was undertaken using Kolmogorov–Smirnov, t, and Scheffé's tests and one-way analysis of variance.

A statistically significant gender difference was found in anterior ratio (P = 0.017). A significant difference in the overall and posterior ratio was observed between Class II and Class III subjects. There was a tendency for mandibular tooth size excess in subjects with an Angle Class III malocclusion and for maxillary tooth size excess in those with an Angle Class II malocclusion. The percentage of subjects more than 2 standard deviations from Bolton's means for anterior and overall ratios was 16.28 and 4.32, respectively.

The lingually inclined, crowded lateral incisor presented an extrusive and buccal movement and showed the lowest force in the vertical direction, whereas the self-ligating group of brackets generated the highest force in the buccolingual direction. The moments applied by the three bracket systems followed the general trend shown for forces; in the vertical axis, the self-ligating brackets exerted lower forces than their conventional counterpart. This was modified in the buccolingual direction where, in most instances, the self-ligating appliances applied higher moments compared with the conventional bracket. In most cases, the magnitude of forces and moments ranged between 30–70 cN and 2–6 N mm, respectively. However, maximum forces and moments developed at the lateral incisor were almost four times higher than the average.

This review summarizes the adaptive response of jaw muscles to various stimuli or perturbations in the orofacial system and addresses general changes in muscles as they adapt, specific adaptive changes in jaw muscles under various physiologic and pathologic conditions, and their adaptive response to non-surgical and surgical therapeutic interventions.

Although the jaw muscles are used concertedly in the masticatory system, their adaptive changes are not always uniform and vary with the nature, intensity, and duration of the stimulus. In general, stretch, increases neuromuscular activity, and resistance training result in hypertrophy, elicits increases in mitochondrial content and cross-sectional area of the fibres, and may change the fibre-type composition of the muscle towards a larger percentage of slow-type fibres. In contrast, changes in the opposite direction occur when neuromuscular activity is reduced, the muscle is immobilized in a shortened position, or paralysed. The broad range of stimuli that affect the properties of jaw muscles might help explain the large variability in the anatomical and physiological characteristics found among individuals, muscles, and muscle portions.

Anterior coronoid marginal depth correlated negatively (r = 0.71) with gonial angle, SNA, and overjet. The coronoid angle also correlated negatively (r = 0.86) with both the vertical and horizontal lengths from sella to the coronoid tip as well as with the horizontal length from sella to the posterior ramus margin. Furthermore, the coronoid length correlated positively (r = 0.61) with the coronoid angle and the anterior coronoid marginal depth. The coronoid width was also positively (r = 0.69) correlated with overbite.

Coronoid process morphology is related not only to mandibular morphology and position but also to maxillary position and the dental relationship in the anterior region. It therefore seems clear that coronoid process morphology might be related to temporal muscle functioning and its associated craniofacial morphological measurements.

The experimental connector is easily constructed, inexpensive, and small enough for use as an intraoral MAS. To evaluate durability, the axial and diagonal tensile breaking strengths of the MAS, using high- or low-density polyethylene (HDPE or LDPE) lateral toothed belts, were compared with those of a conventional mobile MAS (Silensor). The values were compared by factorial analysis of variances and post hoc Scheffe's S multiple comparison intervals, with the value of statistical significance set at alpha = 0.05. In addition, the experimental LDPE connectors were clinically tested in 30 patients (23 males and 7 females aged 19–71 years) and evaluated.

Compared with the Silensor, the experimental MAS exhibited sufficient breaking strength, especially when a diagonal tensile load was applied to mimic mandibular lateral translation. When examining the clinical evaluation between 3 and 4 months after insertion, no damage or failure was observed.

The experimental connecting system may have clinical applications. To make the connector stronger for clinical use, HDPE should be used.

Five identical appliances were manufactured from three different materials all with a thickness of 1.0 mm (Ideal Clear®, Erkodur®, and Biolon®). For measuring the forces, an isolated measuring tooth, as part of a standardized resin model incorporated in a newly developed measuring device, was tipped in nine arc minute ( degree) steps, from 0 to degrees in the vestibular and palatal directions around a rotational axis through the virtual apex, after positioning an appliance on the model. For statistical analysis, the force components Fx/tipping and Fz/intrusion at a displacement of ±0.151 mm from the incisor edge were determined. Means and standard deviations (SDs) were calculated. The Kruskal–Wallis test for overall effects and the Wilcoxon two-sample test for individual group pairings were used (P < 0.05 significance level).

The mean Fx forces ranged from –2.82 N (SD 0.62) to 5.42 N (SD 0.56). The mean Fz forces were between –0.14 N (SD 0.52) and –2.3 N (SD 0.43). The highest intrusive forces were measured during vestibular displacement of the measuring tooth. The forces delivered by the Biolon® appliance were found to be much greater (P < 0.01) than those of the other materials.

The forces delivered by the materials investigated were mostly higher than those stated in the literature.

Single or multiple hypodontia was diagnosed in 137 patients (6.5 per cent), 62 males and 75 females. One or more supernumerary teeth were found in 42 patients (2 per cent), 22 males and 20 females. CHH was diagnosed in seven subjects (0.33 per cent), four males and three females. In the CHH subpopulation, the total number of absent and supernumerary teeth was nine and eight, respectively. Hypodontia always occurred in the permanent dentition and was more frequent in the mandible than in the maxilla (four versus three teeth). Supernumerary teeth were more frequent in the permanent than in the primary dentition (six versus two teeth). Five supernumeraries were located in the maxilla and three in the mandible.

Bleeding on probing (BOP), plaque index (PI), and pocket probing depth (PPD) were measured in 10 adults (8 females and 2 males, aged 29.0 ± 4.7 years) who received treatment with custom-made lingual appliances (Incognito/iBraces) before (T₀) and 3 months after beginning of treatment (T₁). No supportive dental prophylaxis was undertaken. In addition, a 16S rRNA-based polymerase chain reaction (PCR) method was used to detect Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) in the crevicular fluid. A Wilcoxon test was used to compare clinical parameters at the buccal (control) and lingual sites between T₀ and T₁.

At T₀, BOP was 12.4 ± 8.2 per cent, PPD 2.1 ± 0.3 mm, and PI 0.1 ± 0.2 at the buccal sites and at T₁ 14.3 ± 8.1 per cent, 2.1 ± 0.2 mm and 0.1 ± 0.2, respectively. At the lingual sites, BOP was 22.2 ± 19.0 per cent, PPD 2.3 ± 0.3 mm, and PI 0.1 ± 0.2 at T₀ and at T₁ 56.2 ± 31.6 per cent, 2.9 ± 0.3 mm, and 1.2 ± 1.1, respectively. Differences between T₀ and T₁ were significant for clinical parameters only at the lingual sites. Aa was found in five patients at baseline and in four at T₁, whereas Pg was found in one patient at T₀ and in two at T₁.

Insertion of fixed lingual appliances without supportive dental prophylaxis induced a worsening of clinical parameters restricted to the lingual sites, whereas the relative prevalence of Aa and Pg remained unchanged.

One-way analysis of variance showed a significant effect of ligation mode on the frictional properties of the three-bracket set-ups (P < 0.001). Post hoc pairwise comparison showed that the frictional forces arising from passive self-ligation were significantly lower (P < 0.01) than those resulting from elastic ligation. The same result was achieved when comparing self-ligation and metallic ligation (P < 0.01). No significant difference was found when comparing elastic and metallic ligation.

Little or no microleakage was observed between the composite–enamel interfaces for the three investigated composites, and any difference was not statistically significant. However, statistically significant differences were found between microleakage at the composite–wire interface for both the conventional and flowable composite groups (P < 0.001). Flowable composite showed the highest leakage (mean: 4.8 ± 0.8 mm), while Transbond XT (mean: 0.5 ± 0.3 mm) and Transbond LR (mean: 1.1 ± 1.2 mm) showed significantly lower and comparable results. The amount of microleakage at the wire–composite interface was significantly greater than that at the enamel–composite interface of flexible spiral wire retainers (FSWRs). The null hypothesis is therefore rejected. Flowable composites may not be appropriate for bonding FSWRs.

Little or no microleakage was observed between the composite–enamel interface for any of the three groups, and any difference was not statistically significant. The amount of microleakage at the wire–composite interface was higher than that at the enamel–composite interface. Multiple comparison testing showed statistically significant differences in microleakage between Transbond LR and the ACP-containing adhesive used with primer at the composite–enamel and composite–wire interfaces (P < 0.001). ACP-containing adhesive used with primer showed the highest microleakage scores at the composite–enamel (mean: 0.39 ± 0.42 mm) and composite–wire (mean: 1.66 ± 0.47 mm) interfaces. The hypothesis is rejected. The ACP-containing composite used with or without primer showed significantly higher leakage at the composite–wire interface, while conventional lingual retainer composite showed lower microleakage scores.

Statistical analysis showed that the bond strengths of the control (Transbond LR, mean: 24.77 ± 9.25 MPa) and Clearfil Protect Bond with etching, (mean: 20.24 ± 8.5 MPa) were significantly higher than Clearfil Protect Bond without etching, (mean: 12.56 ± 6.93 MPa). In general, a greater percentage of the fractures were adhesive, at the tooth–composite interface (60–65 per cent). No statistically significant difference was found among the groups. The hypothesis is thus rejected. Within the limits of this in vitro model, antibacterial monomer-containing self-etch adhesive with acid etching did not significantly affect shear bond strength when compared with the control. However, the same adhesive used without acid etching resulted in a significant decrease in bond strength.

It was evident that the ability to produce certain facial expressions differs between groups of individuals due to gender and age. Males had a greater upward vertical movement capacity in the studied facial expressions than females. Females had a more pronounced horizontal component in the posed smile. There was a trend from childhood to adulthood showing an increase in the percentage change in most vertical movements. This trend was present in both genders, though more pronounced in males.

Using a robust quantitative method for collecting and analysing facial expressions, gender differences in adults were detected as well as differences between adults and children. The trend toward increasing vertical movements in adults compared with children suggests the possibility that the mimic musculature is developmentally regulated.

The results showed that 63.8 per cent (62.6 per cent in Kinondoni and 66.0 per cent in Temeke) of the subjects had at least one type of anomaly, with a midline shift (22.5 per cent), spacing of at least 2 mm (21.9 per cent), and an open bite (16.1 per cent) being the most frequently recorded. The majority (93.6 per cent) of the children showed a Class I molar relationship. Class II and Class III malocclusions were registered in 4.4 and 2.0 per cent, respectively. Multiple logistic regression analyses, controlling for socio-demographic factors, showed that the odds ratio for having an open bite was 1.8 if residing in a less socio-economically privileged district. Subjects with decayed, missing, and filled teeth (DNFT) (>0) were 1.7, 2.1, 2.4, and 1.7, respectively, more likely to be diagnosed with a malocclusion, a midline shift, Angle Class II and III, and an open bite. Schoolchildren with fair/poor oral hygiene were less likely than their counterparts with good oral hygiene to be diagnosed with a midline shift.

Malocclusions were prevalent in the Tanzanian children investigated and were associated with environmental factors in terms of caries experience and residing in a less affluent district. Preventive programmes to combat the prevalence of malocclusion are recommended.

According to the classification of Angle, the prevalence of Class I, Class II division 1, Class II division 2, and Class III malocclusions was 41.8, 24.1, 3.4, and 7.8 per cent, respectively. Symmetric molar relationship was present in 69.5 per cent. An OJ of at least 3.5 mm or more was present in 28.1 per cent; an OJ of more than 6 mm in 3.6 per cent, and 4.2 per cent had a reverse OJ. A normal overbite was observed in 60.4 per cent, while 34.5 per cent had an increased and 2.2 per cent a very deep overbite. An anterior open bite (AOB) was present in 1.6 per cent and a scissor bite or anterior crossbite in 2 and 8.4 per cent, respectively. A posterior crossbite was observed in 12.4 per cent (8.4 per cent unilateral, 2 per cent bilateral, and 2 per cent in association with an anterior crossbite). Midline deviation was present in 23.7 per cent. Severe crowding (≥5.1 mm) was observed in 16.7 and 10.8 per cent and spacing in 18.9 and 20.7 per cent of the maxillary and mandibular arches, respectively. Significant gender differences were found for overbite (P < 0.001), midline deviation (P < 0.05), and maxillary and mandibular arch crowding/spacing (P < 0.05). The prevalence of Class II malocclusions was comparable with Caucasians; however, the most severe forms of Class II malocclusions were rare in this Iranian population. The relative prevalence of Class III malocclusions in the present study was greater than in Caucasians. Crowding was the most common dental anomaly in both arches.

There were no statistically significant differences between the Jordanian males and females for any of the OQoLQ or SF-36 items; hence, the groups were combined for analysis. When comparing the OQoL data with that of the British sample, there was no statistically significant differences for three of the four domains: dentofacial aesthetics (P = 0.726), social aspects (P = 0.096), or the awareness of dentofacial aesthetics (P = 0.066). There was, however, a significant difference for oral function (P = 0.016), with the Jordanian group reporting a poorer quality of life (QoL) (mean value 10.9) than the British cohort (mean value 8.4). However, it is questionable whether this difference would be of clinical relevance. While it was not possible to directly compare the results of the SF-36 questionnaires with the same British cohort, Jordanian patients had generally lower scores, and therefore a poorer QoL, than reported in other studies. These differences may be cultural or may be due to differences in the health care system’s criteria for funding, and this needs further investigation.

The cumulative incidence rate of treatment requests was 2/54 in the treatment group and 11/58 in the control group. The relative risk was 5.12. The 95 per cent confidence limits were 1.14 and 23.1, respectively. The difference between groups was statistically significant (P = 0.0336).

Systematic elimination of occlusal interferences significantly reduced the incidence of requests for treatment of symptoms in the head and cervicobrachial region. This is in contrast with the view that there is no, or at best, an insignificant health risk from occlusal interferences.

Lateral cephalograms were obtained of 323 Japanese males and 611 females aged 2 years or older but under 25 years of age. Each dataset was divided into 2 year intervals according to age and categorized into 10 developmental stages. One-way analysis of variance followed by a Bonferroni's t-test was used to compare the results for each group of males and females separately.

No significant gender differences were observed in the palatal plane to Ar–Gn plane angle. In males, significant increases in the palatal plane to A–B angle were found up to 14–15 years of age and in the area of abc, G–G' and Ms–Ms' values up to 16–17 years. Among females, changes in these cephalometric measurements showed tendencies that were nearly identical to those of males.

These findings provide the characteristics of Class III malocclusions in the growth and developmental period, and as they can be used as standards for understanding the effectiveness of Class III treatment, they may be useful in orthodontic and/or orthopaedic diagnosis and treatment planning.

The above cephalometric analyses, classic and normalized, were applied to 71 patients [26 males: mean age 13.1 years, standard deviation (SD) 1.1 years and 45 females: mean age of 14.6 years, SD 8.2 years]. Spearman’s rank correlation coefficient was calculated between the classic measurements and their normalized counterparts, resulting in a consistent increase in the correlation between the normalized measurements in comparison with the classic ones. This increase varied in absolute value from 0.052 to 0.405. All normalized measurements were highly correlated (P > 0.742, absolute value).

Although correlation calculations do not represent a true measure of diagnostic performance, it is hoped that improving their correspondence heightens the possibility of the different tests agreeing on the patient's sagittal discrepancy, decreasing the possibility of differing, or even totally opposing diagnostic outcomes resulting from their application to (clear-cut) Class I, II, and III patients.

ANOVA showed statistically significant differences for most of the skeletal variables, but only for lower incisor height and inclination among the dentoalveolar parameters. Correlation analyses demonstrated significant relationships between various skeletal variables. LI–MP showed a negative relationship with SN–MP, whereas LAMdH demonstrated a positive linear relationship with SN–MP. Among all dentoalveolar heights, UAMxH showed the weakest, and LAMdH the strongest, associations with skeletal parameters. The variability in dentoalveolar compensation therefore demands individualized diagnosis and treatment planning. LAMdH and LI–MP parameters were the most likely, whereas UAMxH was the least likely parameter to compensate for vertical dysplasia.

Both operators were generally consistent in the repeated measurements; however, for one examiner, the differences for NaA (P < 0.001), NaPog, and U1–NA (P < 0.01) distance measurements were found to be statistically significant. Intra-examiner repeatability of landmarks both with the manual and Dolphin techniques showed high correlation coefficients. While inter-examiner reproducibility of landmarks was unacceptable, measurement errors with the manual technique were generally comparable with the Dolphin technique. The mean tracing times of the two operators for a single tracing was 2 minutes 41 seconds for Dolphin and 6 minutes 51 seconds for manual tracings. Computer-assisted cephalometric analysis does not increase intra- and inter-examiner reliability but can result in time saving.

GCF samples were collected from eight orthodontic patients wearing fixed appliances with superelastic nickel-titanium coil springs. The samples were analysed by gelatin zymography, which allows detection of both active and latent MMPs, and reverse zymography for analysis of TIMPs. Western blotting was performed to confirm the identity of MMPs. The data were analysed using either the one-way analysis of variance or the Kruskal–Wallis test.

In general, higher levels of MMPs and TIMPs were found at both the resorption and apposition sides compared with the control teeth. Remarkably, partially active MMP-1 was found in GCF from both the resorption and the apposition side but was barely present at the control teeth. TIMP-1 was strongly increased at the apposition side. Gelatinases were mainly present at the resorption side, while gelatinolytic fragments were exclusively detected at the apposition side. MMP-9, which is known to be involved in bone degradation, and a 48 kDa gelatinase were increased at the resorption side. The small increase in TIMP-1 at the resorption side might stimulate bone resorption, whereas the large increase at the apposition side reduces bone resorption. The analysis of MMPs and TIMPs may contribute to the improvement of orthodontic treatment regimens.

Chi-square analysis showed that the frequency of this mutation did not differ statistically between the normal and mandibular protrusion subjects. Multilevel model analysis of the 101 cephalograms showed that the mutation reduced the linear measurements of the mandible. These findings suggest that P561T heterozygous mutation affects mandibular growth during early childhood, and this mutation in the GHR gene is hypothesized to function as an inhibitory factor in the process of mandibular growth.

The ligatures evaluated did not differ significantly from each other regarding biofilm weight, total bacteria, total streptococci, mutans streptococci, or lactobacilli counts (P > 0.05, Wilcoxon paired test). Enamel demineralization was also not different around the brackets for the different ligation methods (P > 0.05, split-split-plot analysis of variance). However, a statistical power analysis based on the data showed a trend to higher demineralization around brackets ligated with elastomeric rings. The developed modified in situ model may be suitable to assess the caries potential of clinical procedures used in orthodontic treatment.

Lateral cephalograms and corresponding dental casts were obtained from 39 untreated Caucasians (12 males, 27 females; mean age 19.5 years; standard deviation 3.7 years) with occlusal relationships considered to be ‘normal’. The upper (U1) and lower (L1) incisors were assessed with reference to the occlusal plane perpendicular which was established on the lateral radiographs, including third order angles (U1TR, L1TR) which were also derived from direct dental cast measurements (U1TA, L1TA). Both single regression and multiple linear regression analysis with stepwise variable selection were performed using third order measurements on casts as the dependent variable and crown axis (U1C, L1C), root axis (U1R, L1R), tip–apex connecting line (U1E, L1E), and radiographic third order measurements as independent variables.

Single regression analysis indicated an overall difference of 0.02 degrees between radiographic third order inclination and cast assessment in the maxilla (mandible: –2.83 degrees). A change of 1 degree in radiographic third order inclination would produce a change of 0.65 degrees for U1TA and 0.86 degrees for L1TA assessments. Third order measurements on dental casts can best be explained by a linear combination of U1TR and U1E (maxilla) and of L1TR and L1C (mandible) measurements.

This study demonstrates the functional enmeshment between two different third order assessments and the most common incisor features on lateral radiographs. Both methods of third order evaluation show sufficient reliability and are appropriate for routine orthodontic practice.

There were significant differences in discolouration depending on the type of elastomeric modules, immersion solution, and immersion period (P < 0.05). The range of colour changes ($$\mathrm{\Delta }{E}_{ab}^{*}$$) was 1.0–20.0 units for AO, 0.6–30.0 units for OC, and 1.1–18.8 units for TP, independent of immersion solution and time. Methylene blue resulted in the greatest colour change. Discolouration due to chemical degradation by the ethanol solution mainly occurred in the first few hours, reached a plateau with no further increase over time, and was greater than staining by methylene blue in that period. Discolouration due to staining by methylene blue, however, continued to increase over the whole immersion period. Therefore, discolouration of elastomeric modules was a result of chemical degradation as well as staining in the early stages but in the later stages was due only to simple staining.

Teeth in G1 and G2 had significantly more resorptive lesions, 55 and 64 per cent, respectively, than the controls of 11 per cent. Resorption was observed over the whole root surface and increased with time. The occurrence increased to 100 per cent in both experimental groups after 36 days of intrusion. The appearance of lesions in relation to root development showed no differences between G1 and G2. In the apical part of the root, total resorption of the dentine was sometimes observed, but no resorptions extended into the predentine. Resorptive lesions undergoing repair were seen in both groups, with significantly more repair in G2 (58 per cent) than in G1 (32 per cent). Active resorption and repair were sometimes seen at the same resorption site. Deposition of cellular and acellular cementum was found to the same extent over the whole root when repair took place. With time, resorption appeared over the whole root surface. In some teeth, resorptive activity continued up to 10 days after removal of forces but on the other hand, repair of the resorbed area sometimes started during active movement. The individual variation in repair was much wider compared with resorption. The predentine layer in the apical area appeared not to be affected by the resorptive process.

The CB children had statistically significantly greater asymmetry of the face (P = 0.042), especially the lower third (P = 0.039), and a significantly smaller palatal volume (P = 0.045) than the NCB subjects at baseline. There were no statistically significant differences between the two groups at T1. Treatment of a CB in the primary dentition corrected the facial asymmetry, particularly the lower part of the face. The palatal volume of the CB children increased as a result of orthodontic intervention to similar levels exhibited by the NCB children.

A posterior crossbite was observed as early as 18 months of age. The prevalence of a posterior crossbite was 10.4 per cent and was associated with age (P = 0.00) and with sucking habits (P = 0.01). The prevalence of sucking habits was 43.5 per cent. A posterior crossbite was not associated with socio-economic status (P = 0.38). While sucking habits were common among the age group studied (43.5 per cent), only a small percentage exhibited a posterior crossbite. These results suggest that further investigations into other aetiological factors, in particular genetics and respiratory problems, are necessary to provide more evidence that could clarify this issue.

Unweighted kappa statistics revealed good intraoperator agreement for the two examiners and a moderate level of interexaminer agreement. Forty-six and 41 per cent of the sample still scored either an MIOTN grade 4 or 5 (i.e. a great or very great need of orthodontic treatment). However, 20 and 25 per cent of the subjects were graded with a MIOTN score of 1 or 2, indicating little or no need for treatment when the PIC was not taken into consideration. This finding emphasizes the importance of early diagnosis of an impacted canine and the need to institute interceptive measures where necessary, as up to 25 per cent of patients might otherwise require no other orthodontic treatment.

PDCs occurred most frequently in subjects with a Class I occlusion. Sixteen per cent of the PDC subjects had congenital absence or peg-shaped lateral incisors or congenital absence of the second premolar, demonstrating a clear association between palatal impaction of the maxillary canine and anomalous or congenital tooth absence. The overjet was significantly smaller in the PDC female subjects, especially in those with unilateral impaction (P < 0.05). Overbite was significantly greater in PDC male subjects compared with the controls, especially in bilateral impaction cases. There was no statistically significant difference between the groups with regard to the maxillary transverse dimensions, maxillary MD widths, or palatal height for either gender.

Thirteen subjects had permanent canine agenesis. The overall prevalence was 0.29 per cent. The prevalence of permanent canine agenesis was 0.27 per cent in the maxilla and 0.09 per cent in the mandible (P < 0.01). The male-to-female ratio was 1:2.2. Dental anomalies associated with permanent canine agenesis were found: 11 patients had retention of the primary canines, 10 other types of agenesis of the permanent teeth, one a primary supernumerary tooth, one a supernumerary cusp, and nine occlusal disturbances.

The results showed that pain was reported for a period of 9 days after archwire insertion. Patients treated with self-ligating brackets reported the highest pain intensity on the day following placement of the first archwire (VAS mean = 42.6), while those treated with conventional brackets experienced the greatest pain intensity at placement of the first archwire (VAS mean = 52) and after the second orthodontic appointment (VAS mean = 59.6). Analgesics were used by 16.5 per cent of patients treated with self-ligating brackets and by 10 per cent of those treated with conventional brackets, most often during the first 2 days after archwire placement. Patients treated with conventional brackets reported significantly more ‘constant’ pain than those treated with self-ligating brackets who complained of ‘chewing/biting’ pain.

Pain appears to be common during orthodontic treatment but perhaps less intense when self-ligating brackets are used, although no difference was observed in the use of analgesics between those treated with self-ligating or conventional brackets. There were no reports of pain after 7–9 days in either group.

The brackets were bonded with Transbond XT to 90 extracted human premolar teeth and divided equally into six groups, that is, black, mint–mate herbal, mint–lemon herbal, and rosehip fruit tea and two control groups, Coca-Cola and distilled water. All groups were conditioned for three 5-minute sessions with equal intervening intervals for 90 days. The initial pH, SBS, and adhesive remnant index (ARI) of the groups were evaluated and the data were analysed statistically by Kruskal–Wallis and Mann–Whitney U-tests, one-way analysis of variance, and Duncan and Z-tests, respectively.

Rosehip fruit tea (2.4 ± 0.07) and Coca-Cola (2.5 ± 0.05) had the lowest pH values. Coca-Cola (6.04 ± 1.11 MPa) and rosehip fruit tea (7.26 ± 1.11 MPa) significantly reduced the SBS to enamel (P < 0.001). The SBS results for the other groups were similar (P > 0.05). Except for the Coca-Cola group (ARI score = 0), fracture sites for all other groups were similar with the majority of bond failures at the enamel–adhesive interface (ARI score = 1).

Although this experiment could not completely replicate the complex oral environment, it seems to confirm that Coca-Cola and rosehip fruit tea may be a causative factor in bracket–enamel bonding failure.

Without thermocycling, microleakage at the enamel–adhesive interface was significantly greater for Admira-Flow than for X-Flow (P < 0.005). At the adhesive–bracket interface, there were no significant differences (P > 0.005). After thermocycling, microleakage of Beautiful-Flow at the enamel–adhesive interface was significantly less than for the other materials tested (P < 0.005), while at the adhesive–bracket interface, Admira-Flow and X-Flow showed significantly more microleakage than Beautiful-Flow and Transbond XT (P < 0.005). Analysis of the effect of thermocycling on each material showed that microleakage increased significantly at the enamel–adhesive interface with Transbond XT (P < 0.05), decreased with Beautiful-Flow (P < 0.05), increased significantly at both interfaces with X-Flow, but not to a statistically significant level with Dyract-Flow and Admira-Flow (P > 0.05). The giomer, Beautiful-Flow, demonstrated the best performance after thermocycling, while composite resins and, in particular, the flowables showed a poorer performance.

Seventy-five non-carious premolars were randomly divided into five equal groups. The brackets were bonded with five different adhesives (Transbond XT, Eagle Bond, Light Bond, Blugloo, Unite) and subjected to artificial accelerated photoageing for 24 hours. The enamel surfaces were colourimetrically evaluated before bonding, following debonding and cleaning with a tungsten carbide bur, after polishing with Stainbuster, and after photoageing of the debonded enamel surface. The Commission Internationale de l’Eclairage(CIE) colour parameters (L*a*b*) were recorded and colour differences (E) were calculated. The results were statistically analyzed using the Kruskall–Wallis test. Further investigation among subgroups was performed using Dunn's multiple correlation test (P < 0.05). The clinical detection threshold for E value was set at 3.7 units.

E values between the first and second measurements showed an increase in the Transbond XT, Eagle Bond, and Light Bond groups. The highest E value was 1.51 ± 1.15 in the Transbond XT group. No clinically significant E value was observed.

Colour changes of orthodontic bonding systems induced by photoageing cannot be clinically observed. Polishing with Stainbuster eliminates enamel surface roughness, which may improve light reflection.

Eighty deglazed feldspathic porcelain discs with a diameter of 10 mm and a thickness of 2 mm mounted in acrylic resin blocks were randomly divided into four groups. In groups 1 and 2, the porcelain surfaces were etched with 9.6 per cent hydrofluoric (HF) acid and in groups 3 and 4 with 5 per cent HF acid. In groups 1 and 3, the Dynalock maxillary central incisor brackets were bonded with Pulpdent silane and Unite bonding adhesive and in groups 2 and 4 with Reliance silane and Unite. Shear forces were applied to the samples using an Instron universal test machine. The non-parametric Kruskal–Wallis test was used to determine significant differences in bond strengths between the four groups and Dunn's multiple comparison test to compare subgroups.

The mean bond strengths and standard deviations of groups 1 to 4 were 5.51 ± 1.19, 6.54 ± 0.002, 4.55 ± 1.93, and 6.39 ± 0.45 MPa, respectively. Specimens bonded with Reliance showed a statistically significantly higher in vitro bond strength than those bonded with Pulpdent. The concentration of etching gels did not result in any statistically significant difference on the in vitro bond strength when evaluated separately.

A double-blind, randomized crossover study was performed and 24 healthy adolescents (12–16 years) undergoing orthodontic treatment were followed over four periods. During periods 2 and 4 (2 weeks each), the subjects ingested 200 g fruit yogurt containing Bifidobacterium animalis subsp. lactis DN-173010 (2 x 10⁸ colony forming units/g) once daily or a control yogurt without viable bacteria. Periods 1 and 3 were run-in and wash-out periods of 1 and 6 weeks, respectively. Salivary mutans streptococci and lactobacilli were enumerated with chair-side kits before and after the yogurt consumption periods. Pre- and post-treatment values within each regimen were compared with a two-tailed marginal homogeneity test for categorical data.

A statistically significant reduction of salivary mutans streptococci was recorded after probiotic yogurt consumption (P < 0.05), which was in contrast to the control yogurt. No significant alterations of the salivary lactobacilli counts were observed.

Short-term daily consumption of fruit yogurt containing Bifidobacterium animalis subsp. lactis DN-173010 may reduce the levels of mutans streptococci in saliva during orthodontic treatment with fixed appliances.

The mean upper incisor intrusion was 1.92 mm and the mean overbite decrease 2.25 ± 1.73 mm in 4.55 months. Upper incisor angulation resulted in a 1.81 ± 3.84 degree change in U1-PP angle and a 1.22 ± 3.64 degree change in U1-NA angle. However, these were not statistically significant (P > 0.05).

True intrusion can be achieved by application of intrusive forces close to the centre of resistance using miniscrews. However, studies with a larger number of subjects and long-term follow-up are necessary.

The Class II buccal segment relationship was corrected to a Class I in an average period of 9.03 ± 0.62 months in the ZAS group and 9.00 ± 0.76 months in the CH group. Significant distalization was observed for the posterior teeth in both groups (P < 0.001). Distal tipping of all posterior teeth occurred in the CH group (P < 0.001), but only for the molars in the ZAS group (P < 0.001). The upper incisors retroclined, overjet decreased, and the upper and lower lips retruded in both groups. The ZAS provided absolute anchorage for distalization of the maxillary posterior teeth and can be used as an aesthetic and non-compliant alternative to extraoral traction in the treatment of Class II malocclusions.

In the RHG group, despite the applied root torque, the lower incisors showed anterior crown tipping. Labial root displacement was not observed. At T2, this labial tipping partially relapsed. Furthermore, the use of RHG appeared to decrease bone apposition in the anterior part of the symphysis, leading to a reduction in width. Bodily advancement of the lower incisors was not achieved with the application of labial root torque and anteriorly directed force on the mandibular arch. The width limit of the lower anterior apical base should be respected during orthodontic treatment planning.

A questionnaire was sent to all 279 orthodontists working in the Netherlands. The questionnaire consisted of six parts, mainly containing multiple-choice questions. Information as to background data on the individual orthodontist, retention in general, frequency of different types of removable or bonded retainers that were used, retention protocol, and the type and size of the wire used for bonded retainers was assessed. All statistical analyses were performed using Statistical Package for Social Sciences version 12.0.1. Tests for the relationship between two items were based on the chi-square test.

The overall response rate was 91 per cent. Most orthodontists placed a bonded retainer in the upper and lower arch, except when the upper arch was expanded during treatment or when extractions were performed in the upper arch, in which case they placed a removable retainer. Opinions varied with regard to how many hours the removable retainers should be worn and the duration of the retention phase. Contraindications for bonded retainers were given by 96 per cent of the orthodontists, with poor oral hygiene being the most commonly mentioned. As far as bonded retainers were concerned, 84 per cent of the orthodontists preferred permanent retention. Fifty-nine per cent of the orthodontists believed that a practice guideline for retention after orthodontic treatment needs to be developed, which was confirmed by the varied responses in this survey.

The results showed a highly significant correlation between statural growth increases and growth prediction assessed from the hand–wrist radiographs (females: r = 0.68; males: r = 0.7). Concerning craniofacial structures, the increase in mandibular corpus showed the highest correlation with growth prediction (females: r = 0.21; males: r = 0.52), but this association would not allow a reliable growth prediction. There was no significant correlation between growth increases of the cranial base, the maxilla, the ramus, and the effective length of the mandible and growth prediction assessed with the help of hand–wrist radiographs.

As each patient has an individual growth pattern and different craniofacial structures show individual growth potential, it is questionable if quantitative craniofacial growth prediction with the help of hand–wrist radiographs is reliable. However, in an individual case for the assessment of the timing of the growth process, a hand–wrist radiograph can contribute to treatment planning.

Lateral headfilms and coloured profile photographs of 18 skeletal Class III Caucasian adult patients (10 males, 8 females with a mean age of 24.5 years) prior to surgery, and nine adult Caucasian patients (four males, five females with a mean age of 27.4 years) with a dental Class I occlusion and no major skeletal discrepancy were included in the study. The headfilms were hand traced and digitized. Various cephalometric variables were calculated by computer software. Each printed profile photograph was evaluated aesthetically by 18 laypersons and 18 orthodontists using a 10-graded visual analogue scale (VAS) and a standard profile for calibration. Intra-observer reliability was tested and no significant error was found. Paired and unpaired t-tests were used to compare the scores. The association between various cephalometric variables and the PAS was tested.

In general, compared with orthodontists, laypersons were less critical in their evaluation of the Class III profiles (+0.3 grade on the VAS) as well as the reference profiles (+0.7). The reference profiles were found to be more attractive than the Class III profiles by both laypersons and orthodontists (+2.3 grades). The degree of facial concavity had a negatively predictive value for the orthodontists’ and laypersons’ evaluations. The degree of facial concavity together with the steepness of the mandibular plane were negatively predictive factors for the PAS given by the orthodontists.

The lower lip thickness of the Turkish population was lower and menton thickness was greater than Arnett's norms. Turkish subjects have depressed orbital rims, cheek bones, subpupils, upright and thin upper and lower lips, retruded incisors, and pogonion and point B. Most of the Turkish mean harmony values were within the range of Arnett's harmony standards. Soft tissue thicknesses were greater and facial lengths, except upper incisor exposure, were longer in Turkish males than females. These differences between ethnic groups should be taken into consideration when formulating orthodontic/orthognathic treatment plans for patients with dentofacial deformity.