Australian Orthodontic Journal最新文献

Aims: The primary purpose was to evaluate condylar and ramal vertical asymmetry in adolescent patients displaying unilateral posterior (UCB) and bilateral posterior crossbite (BCB) malocclusions. A secondary aim was to compare the findings with a matched control group exhibiting normal occlusion (CG) using cone beam computed tomography (CBCT).

Material and methods: The study groups consisted of (1) 30 patients (Mean age: 14.49 +/- 1.91 years) with a UCB, (2) 29 patients (Mean age: 14.57 +/- 1.84 years) with a BCB, and (3) 36 patients (Mean age: 14.24 +/- 2.42 years) as a matched control group (CG). Condylar, ramal, condylar-plus-ramal height and index measurements were performed using CBCT images following the method of Habets et al. A paired t-test was performed for side comparison in each group. Oneway ANOVA (Analysis of Variance) was used to determine statistically-significant differences between the groups for asymmetry index measurements and Tukey's HSD test was employed for individual group differences.

Results: There was no statistically significant difference in condylar height (CH), ramal height (RH), and condylar plus ramal height (CH + RH) measurements between the right and left sides of the UCB group and CG, except for the RH in the BCB group (p = 0.045). Tukey's HSD test showed that the ramal asymmetry index (RAI) and the condylar plus the ramal asymmetry index (CRAI) were statistically significantly different between the UCB and BCB groups (p = 0.035 and p = 0.015, respectively).

Conclusions: Although the condylar asymmetry index (CAI) values were found to be high in the groups of UCB (13.84 +/- 11.33), BCB (9.38 +/- 8.56), and CG (10.58 +/- 9.48), the comparisons amongst the groups were not statistically significant. The asymmetry between the UCB and BCB groups was observed for RAI and CRAI values, rather than CAI values.

Objective: Beta2-agonist medications are thought to have adverse effects on bone density. Surgical denervation and intramuscular beta2-agonist injections appear to have opposing effects on skeletal muscles. The present study has been designed to assess the effects of denervation of the masseter, intramuscular injection of a beta2-agonist and the combination of both procedures, on bone density in the craniofacial skeleton in rats.

Materials and methods: Sprague-Dawley rats were prepared as four groups: 1. surgical sham + saline injection into the masseter (sham); 2. surgical denervation of the masseter (den.); 3. surgical denervation of the masseter + intramuscular formoterol injection into the affected muscle (den.+form.); 4. intramuscular formoterol injection into the masseter (form.). All specimens were submitted for CT examination and volumetric calculations of the mineralised bone tissue were performed.

Results: The sham and form. groups had a greater volume of mineralised bone in the zygoma on the experimental side compared with the control side. The maxilla on the experimental side had a higher volume of mineralised bone in the den.+form. and form. groups compared with the sham and den. groups. The control side of the maxilla had a higher volume of mineralised bone in the den.+form. and form. groups compared with the den. group only.

Conclusion: Intramuscular administration of formoterol appears to induce a bilateral increase in bone mineral density in the maxilla and the zygoma, likely explained as a secondary effect of the well-described increase in muscle mass and strength associated with beta2-agonist administration.

Introduction: Eruption disturbances, tooth size and specific malocclusions are known to be genetically influenced. The clinical association between these traits may indicate common genetic controls.

Objectives: A cross-sectional clinical study was designed to test the null hypothesis that the maximum mesiodistal crown diameter (MMD) of maxillary and mandibular central and lateral incisors and the prevalence of various classes of incisor relationships (Class I, II/1, II/2 and III) do not differ between the subjects with and without permanent mandibular canine(s) impaction.

Methods: Dental models of 43 subjects diagnosed with mandibular canine(s) impaction (Impaction Group - IG) were compared with those of 86 subjects of a control reference sample (Control Group - CG). Independent t-test and chi-square tests were used to determine the association between mandibular canine(s) impaction and the MMD of the incisors and the incisor relationship, respectively. The likelihood of various incisor relationships between the IG and CG were evaluated according to odds ratios.

Results: A fourfold increase (p < 0.0001) in the overall frequency of Class II/2 incisor relationship was observed in the IG when compared to controls.

Conclusions: The null hypothesis was rejected. Subjects with mandibular canine(s) impaction appeared to be characterised with wider incisors and a remarkably high rate of Class II/2 malocclusion. This information assists the understanding of genetically controlled dental anomalies, which are likely to coexist with mandibular canine(s) impaction.

Objectives: The present study aimed to compare the treatment outcomes of a fixed-functional appliance (Twin-Force Bite Corrector - TFBC) and a conventional removable functional appliance (Activator) in the treatment of skeletal Class II malocclusions.

Methods: The TFBC and Activator Groups each included 10 young adults possessing a skeletal Class II malocclusion, and the treatment outcomes of both groups were quantified and compared, using lateral cephalometric radiographs, with an untreated skeletal Class II Control Group.

Results: A skeletal Class I relationship and a marked reduction in overjet were achieved in both treatment groups; however, the duration of treatment was significantly shorter in the TFBC Group (0.45 years) when compared with the Activator Group (1.37 years) (p < 0.001). Effective length and sagittal positioning of the mandible underwent significant changes in the TFBC and Activator Groups. Vertical facial dimensions increased in each group; however, these increases were significantly greater in the Activator Group when compared to the TFBC and Control Groups (p < 0.05). Dentoalveolar changes also contributed to the reduction in overjet.

Conclusions: Although both appliances succeeded in eliminating the Class II relationship and improving the overjet and overbite, the short treatment time in the TFBC Group raises questions regarding the long-term stability of the results.

Objectives: If a skeletal anterior open bite malocclusion is treated by orthognathic surgery directed only at the mandible, the lower jaw is repositioned upward in a counter-clockwise rotation. However, this procedure has a high risk of relapse. In the present study, the key factors associated with post-surgical stability of corrected skeletal anterior open bite malocclusions were investigated.

Material and methods: Eighteen orthognathic patients were subjected to cephalometric analysis to assess the dental and skeletal changes following mandibular surgery for the correction of an anterior open bite. The patients were divided into two groups, determined by an increase or decrease in nasion-menton (N-Me) distance as a consequence of surgery. Changes in overbite, the displacements of molars and positional changes in Menton were evaluated immediately before and after surgery and after a minimum of one year post-operatively.

Results: The group with a decreased N-Me distance exhibited a significantly greater backward positioning of the mandible. The group with an increased N-Me distance experienced significantly greater dentoalveolar extrusion of the lower molars.

Conclusions: A sufficient mandibular backward repositioning is an effective technique in the prevention of open bite relapse. In addition, it is important not to induce molar extrusion during post-surgical orthodontic treatment to preserve stability of the surgical open bite correction.

Objective: To evaluate the treatment effects and stability of Forsus appliance therapy.

Methods: Thirty-one patients (15 males, 16 females) with a mean age of 15.8 +/- 3.1 years (range 13 to 17.6 years, 15.3 +/- 1.2 years for females and 16.5 +/- 1.6 years for males) were selected. All patients had passed beyond their pubertal growth phase (after CS4 or MP3cap). Lateral cephalograms and threedimensional (3D) models were analysed before treatment (T0), at the end of treatment (T1) and at a follow-up visit (T2). The mean period from T1 to T2 was 25 months and ranged from 17 to 32 months. Tooth position and angulations, together with maxillary and mandibular position, were measured on cephalograms. The inclinations and vertical distance changes of mandibular incisors were measured on a 3D digital model.

Results: The Forsus appliance produced significant skeletal and dental changes during treatment (from T0 to T1). In the sagittal plane, mandibular length (Co-Gn) increased 6.47 mm, the maxillary incisors and molars uprighted (angle U1-SN decreased 8.97 degrees and angle U6-SN decreased 3.51 degrees), the mandibular incisors proclined (angle L1-MP increased 3.93 degrees) and the mandibular molars advanced (L6-SP increased 3.61 mm). In the vertical plane, the maxilla and mandible rotated clockwise (angle PP-SN, angle MP-SN, angle OP-SN increased significantly) and the mandibular molars extruded (L6-MP increased 3.06 mm). All of the changes remained relatively stable after treatment. Cephalometric sagittal and vertical changes affecting the mandibular incisors from T1 to T2 were statistically insignificant (p > 0.05) except for lower incisor extrusion (L1-MP, p < 0.05).

Conclusion: The Forsus appliance induced significant skeletal and dental changes, which remained relatively stable during the observation period. The mandibular incisors, in particular, were stable two years after treatment.

Aim: This case report describes an adult female patient who presented with dental asymmetry associated with bilaterally missing lower first molars, accompanied by extruded and mesially-tipped lower second and third molars. Masticatory dysfunction and temporomandibular joint (TMJ) pain were present during mouth opening and likely related to a posteriorly positioned condyle and anterior disc displacement with reduction.

Methods: Orthodontic treatment consisted of occlusal plane levelling and mandibular repositioning, achieved using a Multiloop Edgewise Archwire (MEAW) technique. Differential MEAW activation on each side and temporary occlusal composite bite blocks on the lower left third molar were necessary to increase the vertical dimension of the Class II side, which allowed extrusion of the left premolars to a Class I relationship.

Results: The bilateral uprighting of the second and third molars was achieved by tip-back wire activation to level the occlusal plane and intrude these teeth. Elastics worn vertically on the right side and Class II elastics on the left side facilitated occlusal correction. Dental implants for fixed prosthetic rehabilitation of the missing lower left first molar were placed to stabilise the posterior occlusion. Articular disc recovery removed TMJ symptoms and the case was finished with stable sagittal and vertical occlusal relationships.

Conclusion: Successful management of a canted occlusal plane and the stabilisation of the posterior occlusion, resulted in a recovery of a displaced articular disc and improvement of facial symmetry.

Aim: A longitudinal casecontrol study, designed to analyse the isolated effect of attached palatal spurs in patients displaying a dentoalveolar anterior open bite, is presented.

Methods: Thirty-one patients (mean age of 13.3 years +/- 3.17 years) underwent a standardised treatment protocol with fixed anterior spurs for 8.3 months. Lateral cephalograms and plaster casts were analysed before (T1) and after spur therapy (T2). The data were tested using paired t-tests with a significance level of p < 0.05.

Results: The cephalometric analysis showed significant elongation of the height of the maxillary (mean +1.22 mm) and the mandibular (mean +1.39 mm) alveolar processes, as well as uprighting of the lower anterior teeth. The plaster cast analysis showed an increase in maxillary intermolar width (mean +0.98 mm) and a decrease in intercanine distance (mean -0.96 mm). The mandibular anterior width and dental arch length reduced. Overall, spur therapy resulted in a significant increase in overjet and overbite.

Conclusion: The use of spurs produced a resolution of the open bite in all patients. Therefore, spurs could be considered an effective mechanism for the management of anterior open bite in selected adolescent patients.