The appliance produced an increase in the intermolar width averaging 0.5 mm after 8 days. Tetracycline uptake in the control rats suggested a rapid turnover of bone in both the interradicular domain and the bone–periodontal ligament interface. In the experimental group, however, incorporation of tetracycline into the interradicular domain was reduced and conventional histology revealed evidence of bone loss and osteopenia, in both the experimental and a group of sham-treated positive controls (with inactive, annealed springs). Serum alkaline phosphatase declined significantly in both experimental and sham-treated groups over the 8-day time course, indicating decreased bone formation. Serum acid phosphatase also declined, suggesting a concomitant decrease in bone resorption. Three-dimensional FE analysis of the stresses generated in the bone following occlusal (2 N) and orthodontic loading showed that the orthodontic force created a constant loading condition shielding some areas of bone from mechanical stress. Areas of low mechanical stimulation were coincident with sites of bone loss observed histologically, while bone mass was preserved in areas with higher levels of loading.

These findings suggest that (1) the osteopenia resulted from stress shielding of the interradicular bone by the appliance, and a consequent reduction in occlusal loading below the critical threshold required for maintaining normal osseous architecture and (2) the mechanostat model can be employed to explain, at least in part, the response of the bone to orthodontic loading.

Mobility was detected in three of the 56 (5.4 per cent) MSIs. The mobile implants were all unloaded controls and showed no BIC. All remaining stable MSIs showed some BIC. However, variation in BIC was large, ranging from 2.2 to 100 per cent. There were no significant (P > 0.05) differences in BIC associated with timing of force application, amount of force applied, or implant location. There was a tendency for less BIC at the coronal level, but the differences between levels were not statistically significant. Within the limits of this study, it is concluded that the timing and amount of force at loading and location of implant placement do not affect BIC. Moreover, it appears that only limited amounts of osseointegration are necessary to ensure implant stability.

Pre-treatment digital cephalometric radiographs of 125 patients were traced using Vistadent 2.1 AT and Jiffy Orthodontic Evaluation (JOE) software programs and by hand tracing of the printouts. Twenty-six anatomical landmarks were defined on each radiograph by a single investigator and 28 variables were calculated. Statistical analysis was undertaken using one-way analysis of variance and multiple group comparisons using Duncan's test at a significance level of 0.05.

Low correlation coefficients indicated poor reproducibility for nasolabial angle for each of the three methods (P > 0.05). Most of the variables showed consistency between the three methods except for nasolabial angle, ANS–Me, APFH, L1–NB, Nperp–Pg, Go–Me, and U1–NA measurements. The findings indicated that most of the cephalometric measurements were highly reproducible with direct digital radiographs using Vistadent 2.1 AT as well as with printouts using both JOE software and hand tracing. Despite the low correlation for some measurements between the Vistadent 2.1 AT, JOE, and hand-tracing methods, most of the commonly used measurements were accurate. The user-friendly and time-saving nature of the computerized method using digital radiographs makes it the preferred option.

Pre- and post-surgical lateral cephalographs of 30 adult patients (12 males and 18 females, median age = 25 years, standard deviation = 8.7) who had undergone orthognathic treatment were scanned into a computer. One operator identified 25 landmarks digitally on the computer display and manually on acetate paper. Measurements on the 60 radiographs were duplicated, and measurement error of each method was determined with interclass correlation. A paired t-test was used to detect differences between the manual and digital methods.

Overall, greater variability in digital cephalometric measurements was found. Differences in Gn’, Li, Si, and Ii–Li measurements between the two methods were statistically (P < 0.05), but not clinically significant.

The findings indicate that the results of the two investigated tracing methods are similar and that digital tracing with FACAD® is reliable and can be used routinely.

Significant differences were found between the two methods for SNB, Wits appraisal, Cd–A, Cd–Gn, FMA, SN–PP, U1–NA (mm), U1–FH, L1–NB (mm), and Li–E plane. No significant differences were found between the two methods in the measurement of treatment changes. Cephalometric measurements of most parameters were reproducible for both methods. Despite some discrepancies in measured values between hand-tracing and the computerized method, any differences were minimal and clinically acceptable.

The as-received wires exhibited an inhomogeneous surface with different surface irregularities resulting from the manufacturing process. For the in vivo archwires, an increase in the variety, type, and number of surface irregularities were observed. Crevice corrosion occurred not only at surface irregularities formed during manufacturing and orthodontic handling but also at the bracket-archwire-contacting surfaces and at the archwire surfaces coated with plaque and food remnants. This corrosion may be linked to the formation of a micro-environment at these locations. In addition, a limited number of signs of degradation induced during in vivo testing due to wear and friction were observed.

Non-parametric tests (Mann–Whitney U) indicated significant differences between the two groups (P < 0.009). Lower bond strengths were found for the silanated group implying that silane agents may be an unnecessary step. However, both groups had a clinically acceptable mean SBS [silanated group = 13.1 megapascals (Mpa), non-silanated group = 19.4 MPa]. Bond failure occurred at the bracket–adhesive interface in both groups. There would appear to be no advantage in using a silane agent when bonding metal orthodontic brackets to filled RCs.

The differences between SBSs analysed at 12 and 24 hours were not significantly different. Although a significant difference (P < 0.01) was observed with conventional and self-etching primer (SEP) adhesive systems, SEP revealed bond strengths higher than clinically accepted limits (6–8 MPa). SEP systems can achieve successful orthodontic bond strengths. The rate of development of the bond strength must be determined to ensure sufficient maturation of orthodontic adhesives before functional loading.

Forty-five (30 fluorosed and 15 non-fluorosed) non-carious fresh human premolar teeth, extracted for orthodontic reasons and without any caries or visible defects, were used in this study. The fluorosed teeth were selected according to the modified Thylstrup and Fejerskov index, which is based on the clinical changes in fluorosed teeth. In groups 1 (fluorosed teeth) and 3 (control), the brackets were bonded with Light Bond composite resin and cured with a halogen light. In group 2, Enhance LC was applied to fluorosed enamel before bonding. After bonding, the SBS of the brackets was tested with a universal testing machine. One-way analysis of variance and Tukey multiple comparison tests were used to compare the SBS of the groups. Any adhesive remaining after debonding was assessed and scored according to the modified adhesive remnant index.

The results showed that while fluorosis significantly reduced the bond strengths of the orthodontic brackets (mean 13.94 ± 3.24 MPa; P < 0.01), Enhance LC significantly increased bond strength on fluorosed enamel (mean 18.22 ± 5.97 Mpa; P < 0.05). Groups 1 and 3 had greater bond failures at the composite–bracket interface, whereas group 2 showed bond failure primarily at the enamel–composite interface.

The values for reliability of the total and weighted ICON scores were generally high for the T₀ sample (range 0.83–0.95) but less high for the T₁ sample (range 0.55–0.85). Differences in total ICON score between plaster and digital models resulted in mostly statistically insignificant values (P values ranging from 0.07 to 0.19), except for observer 1 in the T₁ sample. No statistically different values were found for the total ICON score on either plaster or digital models.

ICON scores performed on computer-based models appear to be as accurate and reliable as ICON scores on plaster models.

In the early group, 70 per cent, and in the late group 42 per cent, of adolescents had a history of orthodontic treatment. General dentists carried out 90 per cent of the treatment in the early group and specialists every third treatment in the late group. An early start resulted in more frequent visits (P = 0.004) and a longer treatment duration (P < 0.001), while later timing resulted in an increase in the number of appliances (P < 0.001).

Overjet exhibited an extreme range between –2 and 12 mm (median values 3–3.5 mm). An increased overjet was more prevalent than a reduced or reverse overjet, and a severely increased overjet greater than 6 mm was a common finding affecting around 5–10 per cent of the children. Similarly, overbite showed considerable variations of between –1 and 9 mm (medians 3–3.5 mm) and males exhibited a significantly larger overbite than females. In Class II malocclusion subjects, overbite was significantly enlarged (on average between 0.5 and 1 mm) when compared with those with a Class I malocclusion. Traumatic contact of the gingiva affected every 14th child. A Class II molar relationship of three-quarter units or more was a frequent finding affecting more than one child in five. In addition, at 9 years of age, 3 per cent of the children exhibited a Class III molar relationship of at least a half unit. The wide range of orthodontically relevant occlusal traits found in the present study underlines the need for orthodontic screening at 9 years of age (or earlier).

In a cross-sectional analytical study, the craniofacial structure and profile based on two-dimensional lateral cephalograms of Southern Chinese hypodontia patients (n = 49, 24 males, 25 females, mean age 16.4 years) and a comparison group without hypodontia (n = 41, 15 males, 26 females, mean age 16.7 years) were compared. The hypodontia patients were divided into three subgroups according to the severity of hypodontia (mild: ≤5, moderate: 6–9, and severe: ≥10 congenitally missing permanent teeth).

All hypodontia patients had a significantly reduced mandibular plane, ANB, and face height compared with the control group (P < 0.05). A significant increase in chin thickness was also observed in the hypodontia patients (P < 0.05). As the severity of hypodontia increased from moderate to severe, a tendency to develop a retrognathic maxilla and a Class III skeletal relationship was noted in addition to the above features, making the already thick chin even more prominent. Statistically significant correlations (Pearson's correlation coefficient) were found between the number of missing teeth and SNA, NAFH, and ANB angles, the mandibular plane, chin thickness, and face height.

In Southern Chinese subjects, hypodontia was associated with a shorter face, a flatter mandibular plane, a more pronounced chin, and a Class III skeletal profile. In severe hypodontia subjects, the maxilla was more retrognathic with a greater predilection to a Class III skeletal relationship.

The results showed some correlation between morphology and muscle function (at a confidence level of 95 per cent). However, as the values of the correlation coefficient (r) were too low to establish associations between variables, it was concluded that the dimensions of the upper lip are not correlated with muscle activity.

In the first experiment, a force of 20 cN was applied to eight canines in five volunteers. The mean tooth movement during 10 weeks was 2.4 mm. In the second experiment, two forces of 20 or 200 cN were applied to maxillary premolars in 12 male subjects (aged 24–31 years) to measure pain intensity for 7 days. Spontaneous and biting pain were recorded every 2–4 hours on a 100 mm visual analogue scale (VAS). Wilcoxon signed-rank test was used for statistical analysis.

Comparing the VAS score at force initiation with the other time points, there was no significant difference in spontaneous pain for either group, or in biting pain for the light-force group. However, biting pain in the heavy-force group during the time period from 6 to 156 hours was significantly (P < 0.05) greater than that at force initiation. Comparing the VAS scores between the light- and heavy-force group, VAS scores for biting pain in the heavy-force group during the time period from 8 to 100 hours was significantly (P < 0.05) greater than that in the light-force group.

A force of 20 cN can move teeth, but pain intensity while biting may be greater approximately 8 hours to 5 days following the application of heavy continuous force compared with light force.

SNA, ANB, OcP-NL, OcP-ML, upper space balance, overbite, overjet, bilateral molar relationship, and L1-NB changed significantly (P ≤ 0.05) during treatment. The changes in overbite, overjet, spatial conditions, and molar relationship were in line with the targeted treatment objectives and within the normal range. Although the change in L1-NB was probably due to treatment, it was not clinically relevant given that the mean final values were close to normal at 22.8 degrees (SD 5.8°) for L1-NB and 95 degrees (SD 8°) for L1-ML.

Isolated orthodontic space closure for bilateral upper lateral incisor aplasia using PPM can be regarded as a valid alternative to prosthetic solutions. Long-term use of Class III elastics does not lead to significant changes in relevant orthodontic parameters.

The addition of RME to fixed appliance therapy caused a change in transverse measurements between the medial aspects of the bilateral rugae. There was no change in antero-posterior measurements (APM). The transverse changes were more marked for the third, less for the second rugae, and the least for the first rugae. The medial aspects of the third rugae cannot be considered as stable reference landmarks for dental cast analysis when RME is performed in addition to fixed appliance therapy.

The findings demonstrated that the two maxillary premolar extraction protocol provided the occlusal outcomes in a shorter time (group 1: 45.7 months, group 2: 23.01 months) and, therefore, demonstrated greater treatment efficiency than the pendulum appliance.

The results verified that continuous changes of the dental arches occur from the primary until the adult period, with individual variations. This change could be interpreted as a biological migration of the dentition, resulting in anterior crowding especially in the mandible, even in subjects with congenitally missing third molars.

The occlusion should be regarded as a dynamic rather than a stable interrelationship between facial structures. This natural development has to be considered in orthodontic treatment planning as well as in assessment of stability following orthodontic treatment. A continuous increase of palatal height up to adulthood seems to be an effect of a slow continuous eruption of the teeth. This finding is also of significance in explaining the infraposition of implant-supported crowns.

Ninety-two teeth were placed directly into favourable positions and left to erupt spontaneously. Forty-seven teeth were transplanted into atrophied jaw sections and underwent post-operative orthodontic adjustment. According to the post-operative treatment performed, the sample was divided into two groups: transplants with or without subsequent orthodontic treatment. The mean post-operative observation time was 4.4 years. Study models were obtained from all patients and the American Board of Orthodontics Objective Grading System was adapted for evaluation of position, occlusion, and interproximal contacts of the transplanted teeth. A Mann–Whitney U-test was used to determine significant intergroup differences with respect to the final scores and the various evaluated criteria.

Absence of occlusal contacts was found in more than 30 per cent, absence of both interproximal contacts in more than 15 per cent, and inadequate position in more than 40 per cent of the transplants without subsequent orthodontic treatment. The poorest results were observed for maxillary teeth transplanted into the mandible.

The results of the present study show that incorrect positioning with absence of occlusal and interproximal contacts are frequent findings in transplanted teeth. Short-term orthodontic adjustment, especially of maxillary transplants into the mandible, seems to be advisable in order to obtain correct positioning and function of these teeth.

The radiographic measurements of the 3D images were closer to the physical measurements than the 2D slices and 2D projection images. No statistically significant difference was found between the ideal and the rotated scan measurements for the 3D images and the 2D tomographic slices. A statistically significant difference (P < 0.001) was observed between the ideal and rotated scan positions for the 2D projection images. The findings indicate that measurements based on 3D CBCT surface images are accurate and that small variations in the patient's head position do not influence measurement accuracy.

Rhinomanometry showed a correlation (r = 0.57) between the size of the nasal pharyngeal area and nasal airflow, but only at 150 daPa. The size of the adenoids measured on the lateral cephalograms was correlated with the endoscopic findings. The size of the adenoids remained the same after RME. Patients with maxillary constriction had the largest adenoids and showed a negative pressure in the middle ear. However, this was reduced after RME.

The results suggest a possible impact of maxillary deficiency on otorhinological structures. RME may lead to otorhinological changes. Further interdisciplinary investigations are needed to corroborate these findings.

At T1, all posterior crossbites were corrected and the expansions were statistically significant. At T2, despite some reduction in the transverse measurements, the posterior crossbites remained corrected. There were no statistically significant differences between the treatment and control groups at T2 regarding transverse measurements, except for the distance between the mesio-buccal cusp tips of the maxillary first molars. In the treatment group, there was no significant difference in terms of reductions in the transverse dimensions over the short- or long-term, no significant correlations between age or gender and the decrease in transverse dimensions or between the degree of anterior and posterior expansion. There were no significant correlations between the degree of expansion and subsequent post-treatment decrease.

The results indicate that SARME normalizes the transverse discrepancies and is stable a mean of 6 years post-treatment. The decreases in the transverse dimensions are most pronounced during the first 3 years post-treatment.

A good correlation (0.95) was found, as shown by Cohen's kappa. To evaluate the relationship between dental age estimated by Häävikko's standards and the chronological age of the Italian sample, Bland and Altman's graphical method was employed. Moreover, centiles of dental age were constructed both for girls and boys using the LMS (L = skewness, M = median, S = coefficient of variation) method of Cole and Green.

It was found that Häävikko's standards tended to underestimate chronological age in this Italian sample. Dental maturation standards as described by Häävikko do not appear suitable for Italian children; instead, centile curves constructed for girls and boys using the LMS method could be used for the estimation of dental age in the Italian population.

Generally, agreement between the information obtained from study models versus photographs of study models was high with k values being above 0.70 for most variables. The exception to this was overbite with k values ranging from 0.66 to 0.74. When ICCs were considered, again the two methods compared very favourably.

Children with diagnosed OSA had a significantly increased overjet, a reduced overbite, and narrower upper and shorter lower dental arches when compared with the controls. Snoring children had similar but not as significant differences as OSA children when compared with the controls. There were more children with an anterior open bite (AOB) in the OSA group (P = 0.016) and with a Class II or asymmetric molar relationship in the groups of OSA (P = 0.013) and snoring (P = 0.004) subjects compared with the non-obstructed controls. There were more subjects with mandibular crowding (P = 0.002) and with an AOB (P = 0.019) with an increasing obstructive apnoea–hypopnoea index (AHI).

These findings are in agreement with previous studies of the effects of increased upper airway resistance on dental arch morphology and can be explained by long-term changes in the position of the head, mandible, and tongue in order to maintain airway adequacy during sleep.

Weak but statistically significant, negative, correlations were found between awareness of malocclusion and satisfaction at the following DAI scores: ≤25 (r = –0.264, P < 0.001), 26–30 (r = –0.381, P < 0.001), and ≥36 (r = –0.477, P < 0.001), and a statistically insignificant, negative correlation at a score of 31–35 (r = –0.102, P > 0.05). A statistically significant association was found between DAI and awareness of malocclusion (r = –0.305) and satisfaction with dental appearance (r = 0.234). There were no significant associations between the department in which the individuals studied and the investigated variables (P > 0.05). DAI scores were significantly higher for females. Generally, no statistically significant gender differences were found in relation to DAI scores, awareness, or satisfaction (P > 0.05). The findings of this study showed that age had a significant effect on satisfaction and gender on DAI score variation. Females had a greater need for normative treatment except in the 20- to 22-year-olds, and satisfaction decreased with age.

A random sample of 100 Turkish individuals (46 males and 54 females; ages 19–25 years) was obtained. The photographic set-up consisted of a tripod that held a 35 mm camera and a primary flash. The camera was used in its manual position and photographic records were taken of the subjects in natural head posture. The photographic records, 35 mm slide format, were digitized and analyzed using the Quick Ceph Image software program for Windows. Twelve measurements were digitally analyzed on each photograph. For statistical evaluation a Student's t-test was performed and the reliability of the method was analyzed. The results were compared with reported norms of facial aesthetics.

The nasofrontal (G–N–Prn), nasal (Cm–Sn/N–Prn), vertical nasal (N–Prn/TV), and nasal dorsum (N–Mn–Prn) angles showed statistically insignificant gender differences (P > 0.05). The nasolabial angle (Cm–Sn–Ls) demonstrated large variability. Gender differences were present in the mentolabial (Li–Sm–Pg) and cervicomental (G–Pg/C–Me) angles. The mentolabial angle showed a high method error and large variability. Facial (G–Sn–Pg) and total facial (G–Prn–Pg) convexity angles were similar, while Cm–Sn–Ls angle range was larger compared with other angles.

The mean values obtained from this sample can be used for comparison with records of subjects with the same characteristics and following the same photogrammetric technique. Angular photogrammetric profile analysis can provide the orthodontist with a way of determining problems associated with various soft tissue segments of the face.

Orthodontic treatment need, using the DHC, was found in 21.8 per cent of the 12-year-olds and in 17.1 per cent of the 15- to 16-year-olds; and with the AC in 4.4 and 2.4 per cent, respectively. Considering both components together, 23.5 per cent of the population [confidence interval (CI) 95%: 19.2–28.1] of 12-year-olds and 18.5 per cent (CI 95% 14.2–23.4) of 15- to 16-year-olds had a definite treatment need. No gender dependent differences were found. Spanish orthodontic treatment need is similar to that reported in most recent studies in Europe, with approximately one in five to six children with an orthodontic treatment need.

Two questionnaires were sent to 272 orthodontists in Sweden. In one questionnaire, they were asked to grade different malocclusions (defined in the DHC) according to the need for orthodontic treatment and in the other to provide details of their background. Eighty-one per cent (219) answered one or both questionnaires and 216 answered the questions concerning the need for orthodontic treatment. The Swedish orthodontists’ judgements were then compared with the gradings in the DHC. Statistical analysis was undertaken using chi-square, likelihood ratio chi-square, phi coefficient, contingency coefficient, and Cramer’s V tests.

The result showed that almost all participating orthodontists agreed that grade 1 of the index indicated no need for treatment. For grade 2 (little need), the opinions differed, but still the majority were in agreement with the index. The judgements for malocclusions in grade 3 (borderline need) were widespread, but the majority considered 3a, 3c, and 3f to have a need or a great treatment need. The only statistical correlation with background factors was that female orthodontists graded 3f higher than borderline. For grades 4 and 5 (need and great need), the Swedish orthodontists thought that all the malocclusions required treatment except 4x, which the majority considered to be borderline.

The participating Swedish orthodontists in this study graded fewer malocclusions in grade 3 and the majority were of the opinion that compared with the DHC, more malocclusions needed treatment.

Eighty-eight patients (26.3 ± 8.4 years) completed the questionnaire. After the initial treatment, 36 per cent of the patients did not have any retention measures. The mean VAS scores for dental aesthetics at the start and end of the initial treatment were 2.3 ± 2.1 and 6.6 ± 2.7, respectively. The scores for the present situation and expected results of re-treatment were 4.1 ± 2.7 and 8.8 ± 1, respectively. These scores differed significantly from each other. Seventy-nine pairs of models were matched for evaluation of treatment need and complexity. The mean ICON scores of the re-treatment group were significantly lower than the controls (45 ± 21 versus 57 ± 24), the aesthetic component being the main contributing factor to this difference (25 ± 16 versus 36 ± 18). Both groups showed a treatment need (ICON > 43), with the untreated controls having a relatively higher complexity. These results indicate that patients seeking re-treatment had a good perception of dental aesthetics, strong motivation, and an objective treatment need.

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.

Ten patients (five females and five males, aged 18.3 ± 5.4 years) who had received therapy with fixed orthodontic appliances for 24 ± 9 months were enrolled in the study. Biofilm formation on 28 orthodontic bands was analyzed quantitatively with the Rutherford backscattering detection method, a scanning electron microscopy technique. The biofilm formation for the supra- and subgingival surfaces was calculated from the grey values. Statistical analysis was performed with a mixed model with the patient as the random factor. A P-value <0.05 was considered significant.

A biofilm was found on 16.1 ± 9.2 per cent of supragingival surfaces and on 3.6 ± 4.4 per cent of subgingival surfaces. Differences in biofilm formation in supra- and subgingival surfaces were statistically significant (P < 0.05) and formed a distinct demarcation line. Despite the presence of supragingival biofilm, no mature subgingival biofilm was found on the tested orthodontic bands.

The results showed that the mean SBS to amalgam surfaces were significantly lower than those to etched bovine enamel (P < 0.001). There were no statistically significant differences in mean SBS between the amalgam bonding groups (P > 0.05). For the ARI, significant differences were found between the amalgam- and enamel-bonding groups (P < 0.001).

The mean SBS of stainless steel orthodontic brackets bonded to amalgam surfaces with RMP, PB OLC, OS+ intermediate resins and Unite and Resinomer adhesives was significantly lower than to etched bovine enamel. Bond failure occurred at the amalgam–adhesive interface regardless of the adhesive system and without damage to the amalgam restoration.

The aim of this review is to summarize recent progress in the understanding of pathological alterations occurring during childhood and adolescence that affect the temporomandibular joint (TMJ) and, hence, result in disorders of mandibular growth. Pathological conditions taken into account are subdivided into (1) congenital malformations with associated growth disorders, (2) primary growth disorders, and (3) acquired diseases or trauma with associated growth disorders.

Among the congenital malformations, hemifacial microsomia (HFM) appears to be the principal syndrome entailing severe growth disturbances, whereas growth abnormalities occurring in conjunction with other craniofacial dysplasias seem far less prominent than could be anticipated based on their oftendisfiguring nature. Hemimandibular hyperplasia and elongation undoubtedly constitute the most obscure conditions that are associated with prominent, often unilateral, abnormalities of condylar, and mandibular growth. Finally, disturbances of mandibular growth as a result of juvenile idiopathic arthritits (JIA) and condylar fractures seem to be direct consequences of inflammatory and/or mechanical damage to the condylar cartilage.

An integrated experimental/numerical approach was adopted. Using the photoelastic technique, the stress field arising in the bone after screw insertion and the application of the initial orthodontic load was assessed. The finite element (FE) method was used to determine the stress acting in the bony tissue after a given time following screw application, when, for the viscoelastic relaxation effects, the only stress field remaining was that due to the application of the orthodontic load. Different levels of osseointegration were hypothesized.

Photoelastic analyses showed that stress distribution does not change significantly for moderate initial orthodontic loads. From the FE simulations, it was found that critical conditions occur for screws 14 mm long with an orthodontic load of 2 N. The optimal screw length seems to be 9 mm. For such a dimension, small stress values were found as well as low risk of lesion to the anatomical structures.

Four devices were removed because of loss of stability. A wide variation between animals was found for all parameters. BV/TV: slightly higher values were found in the unloaded sample. Although no particular trend was observed, at 3 months higher values were found in the lower jaw. BIC: a trend to a decrease between 1 week and 1 month followed by a significantly progressive increase was observed. Implants that showed some sections with as little as 3 per cent BIC successfully resisted loading. MS/BS: higher values were found in the lower jaw. MS/BS increased significantly between 1 week and 1 month, followed by a progressive decrease. ES/BS: there was a decrease between 1 week and 1 month, followed by a progressive re-increase.

BV/TV did not show any particular trend while BIC was a time-dependent factor. MS/BS and ES/BS demonstrated opposite trends during the healing period. Immediate loading with light forces did not negatively affect the bone healing pattern.

It appears that there are no major differences in tissue reaction between species during experimental tooth movement. Although hyalinization is considered to be an undesirable side-effect of orthodontic tooth movement, little attention has been paid to the phenomenon itself and its possible relationship with stress/strain levels in the periodontal ligament (PDL) and alveolar bone or the rate after the initial phase of tooth movement. There is a need for well-designed experimental studies to elucidate the role of hyalinization in orthodontic tooth movement.

One day after the start of the experiment, a few blood vessels could be seen in the compressed PDL with forces of 0.8 and 1.6 g. The cross-sectional areas of blood vessels (CAV) and periodontal ligament (CAPL) in the experimental groups where a force of over 4 g was applied were significantly smaller than those where 0.8 and 1.6 g forces were used, and in the control group. On day 7, large CAV were seen in the 1.6, 4, and 8 g groups. On day 28, the 8 and 18 g groups showed significantly larger CAPL than the 0.8, 4 g, or control groups.

The findings suggest that a light continuous force, under 1.6 g, maintains the vascular structure during experimental tooth movement. In contrast, a heavy continuous force over 4 g causes the vascular structure to be absent in the early stages of tooth movement, but a dynamic regeneration of the PDL with vascularity and expansion follows.

The eruption rates of the maxillary incisors in the appliance group were significantly decreased when compared with the control group during the whole experiment. In the appliance group, the eruption rates of the mandibular incisors were decreased more than those of the maxillary incisors (P < 0.01). There was no difference in incisor inclination between the appliance and control groups on day 10 (P = 0.81). The applied force of 25 cN in an antero-posterior direction diminished incisor eruption to a level which enabled a constant direction of orthodontic force for 10 days.

Compared with the age- and gender-matched mixed orthodontic controls, JIA patients showed a significantly greater prevalence of anterior open bites (AOBs; P < 0.05; Wilcoxon matched pairs test). Cephalometrically, a larger mandibular plane (P < 0.05) and SNA (P < 0.001) angles and a smaller interincisal angle (P < 0.001) were found. In comparison with the Class II division 1 controls, JIA patients showed a larger SNA (P < 0.001; Wilcoxon matched pairs test) and SNB (P < 0.05) angles and smaller lower anterior face heights (LAFHs; P < 0.05). No differences were found for the mandibular plane, the gonial and the interincisal angles, or total face height.

From this case–control study, it can be concluded that although JIA patients share occlusal characteristics with non-JIA patients with a Class II division 1 malocclusion, they are different with regard to the prevalence of condylar lesions and AOBs, as well as SNA and SNB angles and LAFH.

Internal morphology: a statistically significant correlation was found between the mental and mandibular angles (correlation coefficient: –0.60, P = 0.0004). When the mental angle was narrow, the mandibular angle tended to be wide, while a wide mental angle was interrelated with a narrow mandibular angle. External morphology: a statistically significant correlation was found between the mandibular and gonial angles (correlation coefficient: 0.57, P = 0.0009). A weaker correlation was also found between the mandibular and β-angles.

The findings show that the internal courses of the mandibular and mental canals are interrelated. They also indicated that the course and morphology of the mandibular canal are interrelated with external mandibular morphology.

The results demonstrated a retropositioning of both the maxilla and mandible (SNA and SNB P < 0.01) and increased mandibular development (Go–Me distance). Vertically, there was a trend to a posterior rotation of the mandible (P < 0.01), resulting in a hyperdivergent profile. This trend was confirmed by the increase in SpA–SpP/Go–Me (P < 0.05). In agreement with previous studies, the effects of surgical closure of a cleft lip might be responsible for excessive maxillary retropositioning with a downward rotation.

Tooth size was reduced in all cleft groups in both jaws, with the smallest teeth being found in the ICP group. Upper lateral incisors on the cleft-affected side in UCLP and BCLP patients showed the greatest reduction in size. The upper central and lateral incisors on the cleft-affected side in the UCLP and BCLP groups were frequently hypoplastic or peg-shaped. Molar morphology in all the cleft groups was similar to that in the control group. Reduced tooth dimensions were found in both jaws in subjects with all types of clefts, suggesting a shared genetic basis. Additionally, the upper incisors were abnormal in morphology in UCLP and BCLP subjects with or without a cleft palate, suggesting shared local aetiological factors.