Volumen 31 (2015): Edición 1 (January 2015)

The aim of this study was to evaluate the dentoskeletal effects of a modified slow maxillary expansion appliance (MSMEA) during the transition from the mixed to the permanent dentition.

Forty subjects presenting with posterior crossbites were divided into two groups. Twenty-three subjects were assigned to a treatment group (mean age: 9.45 years) and 17 subjects assigned to a control group (mean age: 9.25 years). An MSMEA with acrylic occlusal coverage limited to the palatal cusps was used to provide maxillary expansion. The mean slow expansion treatment period was 7.8 months, while the mean observation period continued for 14.8 months of a 22.6-month total study period.

Substantial dental and skeletal effects were observed following treatment with the MSMEA. Most maxillary inter-molar and deciduous inter-second molar width increases were maintained in the permanent dentition (91% and 97%, respectively). Skeletal maxillary transverse dimensions, which increased by 2 mm after active expansion, were significantly greater (p< 0.001) when compared with the controls.

The findings suggested that an MSMEA provided orthopaedic and dental effects as a result of posterior crossbite correction. The effects of the appliance seen during the mixed dentition were maintained in the permanent dentition.

The present study examined the effect of topical fluoride treatment on the shear bond strength (SBS) of orthodontic brackets using single-dose fluoride varnishes and assessed according to different post-application times and the pattern of debond.

Of the 105 extracted human mandibular premolars used in the study, 70 were subjected to the SBS test and the remaining 35 to the Adhesive Remnant Index (ARI) test. The teeth were divided into a control group and six test groups: Kolorz®ClearShield^TM 5%NaFl varnish Day 1, 8, and 15; and VanishTM 5%NaFl varnish Day 1, 8, and 15. The samples were coated with their respective varnish, following which, brackets were bonded. Each specimen was subjected to a shear force in a universal testing machine until failure. Data were analysed using the analysis of variance (ANOVA).

At all time intervals, the mean SBS of the Vanish groups was not significantly different from the control group, and the shear strength in the ClearShield groups was significantly higher than the control and Vanish groups, except at Day 8 (no difference). For the same bonding material, there was no significant difference in mean SBS over different time intervals. ARI scores showed no significant difference between the groups.

The application of single-dose fluoride varnish, irrespective of the length of time between the fluoride treatment and bonding procedure, does not negatively affect the shear bond strength of orthodontic brackets.

There are few reports of the socio-demographic and malocclusion characteristics of those undergoing clinical orthodontic treatment in private specialist practice.

To describe the pretreatment characteristics of individuals presenting for orthodontic treatment.

Individuals (N = 174) presenting for orthodontic treatment in 19 private specialist orthodontic practices in New Zealand were randomly selected and examined (at the beginning of a three-year prospective study) and their malocclusions compared using the Dental Aesthetic Index (DAI).

The mean DAI score was 35.8 (SD 8.4). There were no statistically significant socio-demographic differences in DAI score other than by household-based socio-economic status (SES), whereby mean scores were considerably higher in those of low SES. The majority of patients attending for treatment had severe or very severe/handicapping malocclusions. Females had less severe malocclusions than males, on average, although the difference was not statistically significant.

The malocclusion severity threshold for seeking orthodontic treatment appears to be higher in those of lower SES. The study findings highlight the need to improve access to orthodontic treatment for this group.

This study was undertaken to assess pre- and post-treatment upper and lower arch dimensions, and changes occurring in those dimensions, during orthodontic treatment without premolar extractions, when finishing wires of a particular material, size and arch form had been used.

The records of 58 patients (31 male and 27 female) with a mean age of 13.52 (±1.60) years were selected for this study, with ethics approval gained from the Departmental Human Ethics Advisory Group of the University of Melbourne (DHEAG no: 1033997.1). All patients had been treated with fixed appliances (0.018 inch, pre-adjusted edgewise) in the early permanent dentition, without premolar extractions, by one experienced orthodontist. Pre- and post-treatment upper and lower arch dimensions were measured from study casts. Correlation coefficients were calculated between these measurements as well as pretreatment cast and vertical cephalometric measurements, gender and the amount of crowding that had been relieved.

Despite the use of finishing archwires of the same material, size and arch form (0.016 × 0.022 inch, heat-treated cobalt-chromium), there was considerable variation in dimensional changes that occurred during treatment within the total sample and its various subgroups, and in the final arch dimensions. All arch width changes were found to be strongly correlated with the amount of pretreatment crowding. Post-treatment arch dimensions and changes in those dimensions were also strongly correlated with pretreatment dimensions, suggesting that the final post-treatment arch dimensions were significantly influenced by other factors rather than simply the material, size and arch form of the finishing wires. In this treated sample, no statistically significant differences were found in the resultant arch widths and arch width changes occurring in the different vertical pattern sub-groups.

The placement of finishing wires of a particular material, size and arch form is unlikely to result in exactly matching end-of-treatment arch forms and dimensions in all orthodontic patients. Instead, whether using a 0.018 or a 0.022 inch slot system, the clinician should expect considerable individual variation in final arch form and dimension, despite the placement of apparently very similar wires. The main determinants of final arch form and dimension appear to be the original muscular and occlusally-related arch form and dimension and the amount of crowding to be relieved. Final arch forms and dimensional changes with treatment are unlikely to be directly related to patient gender, age or underlying vertical pattern. The findings indicate that clinicians must decide whether they will accept the considerable lateral and antero-posterior expansion that is likely to occur when crowding is to be relieved in the permanent dentition without premolar extractions.

To determine the features of the mandibular dental arch in subjects presenting with impacted permanent lower canines.

The ‘impaction group’ consisted of 48 Indian subjects with mandibular canine impaction (Females:Males, 1.5:1; mean age, 15.03 ± 0.49 years). The ‘control group’ was comprised of 96 age-, gender- and malocclusion-matched Indians who were randomly selected from subjects initially screened but who had completely erupted mandibular canines. Arch width, arch length, arch shape and space status (total tooth size, arch-length – tooth-size discrepancy) were assessed using dental models and were compared between the groups using comparative measurements and statistics.

Statistically significant differences were demonstrated with respect to the arch length, arch shape, total tooth size and arch-length – tooth-size discrepancy (p = 0.03, 0.02, 0.04, 0.01; independent 2-sample t-tests, respectively). Crowding was more prevalent in subjects with impaction than in the controls, with the difference being statistically significant (chi-square = 13.202; degrees of freedom (df) = 4; p = 0.010).

Patients with permanent mandibular canine impaction have adequately wide but shorter lower dental arch forms along with wider mandibular total tooth size and greater arch-length – tooth-size discrepancy when compared with a control sample.

To evaluate the antibacterial properties and effects of an orthodontic adhesive containing copper nanoparticles (NPs) on the material’s shear bond strength.

Antimicrobial activity was analysed by a disk diffusion test against S. aureus, E. coli and S. mutans. The NPs were added to the orthodontic adhesive at 0.0100 wt%, 0.0075 wt%, and 0.0050 wt%. Sixty extracted bicuspids were divided into two groups and the enamel of all teeth was conditioned with phosphoric acid. A coat of moisture insensitive primer (MIP) was applied prior to the bonding of brackets with composite resin. Group I served as a control and the bonding procedure was performed according to the manufacturer’s instructions. Group II comprised the test teeth, into which 0.0100 wt% copper NPs were included in the MIP Samples were tested and statistically analysed (p ≤ 0.05). The adhesive remnant index (ARI) was also assessed microscopically.

The adhesive with copper NPs showed a bactericidal effect against the bacteria under study. A significantly higher bond strength was obtained with the orthodontic adhesive that included 0.0100 wt% of copper NPs (15.23 ± 6.8 MPa) in comparison with the control group (9.59 ± 4.3 MPa). The ARI scores indicated that the groups were significantly different and strengthened by the incorporation of NPs (p = 0.004).

The results of the present study suggested that an orthodontic adhesive, which included copper NPs, significantly increased material shear bond strength without adverse side effects on colour and appearance. The adhesive interface was strengthened by homogeneously dispersed copper NPs added as a nanofiller.

The present investigation was designed to determine the location and severity of root resorption associated with impacted maxillary canine teeth using cone beam computed tomography (CBCT). A secondary aim was to identify possible influencing factors.

The radiological reports of 183 patients, radiographed with a small-volume CBCT focussed on the impacted maxillary canine teeth, were assessed. Eighty-five patients had resorption associated with the impaction. The CBCT image datasets were viewed to determine the location and severity of the lesions.

A total of 110 impacted maxillary canine teeth resorbed 120 adjacent teeth, including 14 premolars and one permanent molar. The apical third and palatal surface were commonly involved. Fifty per cent of the resorptive lesions were mild, 20% moderate and 30% severe. There was no significant relation between age or gender on the number, location or severity of resorption. There was a statistically significant correlation between the number of impacted canine teeth and the number of teeth resorbed, as well as the tooth type and the surface involved in the resorption.

All root levels and surfaces of teeth associated with impacted maxillary canine teeth can be resorbed to different levels of severity. Neither age nor gender influences the number, location or severity of the resorption.

The present study involved an assessment of the effects of the Herbst appliance used for Class II correction in subjects with different vertical facial patterns.

Pre- and post-treatment lateral cephalograms of 91 growing Class II patients were divided into three vertical facial groups on the basis of mandibular plane angulation. All received a Herbst appliance and dental and skeletal changes were assessed in relation to pretreatment incisal overbite, overjet and the stage of cervical maturity.

Herbst appliance treatment was accompanied by changes in the angulation of the upper and lower incisors, overjet reduction and an increase in mandibular length. In general, the rotational facial changes occurring during treatment were minimal, so that dolichofacial patterns remained long and brachyfacial patterns remained short.

Herbst appliance treatment can be expected to result in considerable Class II dental correction. It is unlikely, however, that its use will be associated with clinically significant forward rotation in dolichofacial subjects. Since dolichofacial patterns are likely to remain long-faced, even after considerable Class II dental correction, orthognathic surgery may still be a consideration if normal facial proportions, without excessive facial convexity and lip strain, are treatment aims.

The present case report describes the orthodontic treatment and long-term follow-up of an adult female patient (27 years) who was diagnosed with a mild Class III malocclusion characterised by an anterior and lateral open bite and three periodontally-compromised first permanent molars.

The aim of treatment was to provide an acceptable aesthetic and functional occlusion while, at the same time, improving the periodontal prognosis.

The patient was treated with fixed orthodontic appliances utilising direct and indirect skeletal anchorage derived from two mini-screws placed in the palate and one mandibular buccal mini-screw.

The objectives of good aesthetics, a functional occlusion, a healthy periodontium and a balanced profile were achieved.

The total treatment time was 31 months, which comprised 13 months of maxillary fixed labial appliances and 25 months of mandibular fixed labial appliances. The three-year follow-up records showed stability of the Class III correction.

The extraction of an upper lateral incisor for orthodontic purposes is rare and must be adequately justified.

The present case report describes the management of a skeletal Class II crowded malocclusion that was facilitated by the extraction of upper lateral incisors and lower first premolars.

A 14-year-old male patient presented with a skeletal Class II crowded malocclusion with associated speech and chewing difficulties. Phase I of treatment involved the extraction of the upper lateral incisors and functional appliance therapy. Phase II included the extraction of lower first premolars and mechanotherapy using full fixed appliances.

An improvement in aesthetics and sagittal relations was achieved during phase I therapy as the mandible was advanced over a period of eight months. Mandibular skeletal change was 6.5 mm observed at pogonion. During phase II therapy, the maxillary canines were substituted for lateral incisors and a functional occlusion was achieved. The skeletal correction and occlusion were stable one year after debonding.

The present case indicated that the timely extraction of palatally-placed maxillary lateral incisors facilitated functional appliance therapy in the management of a skeletal Class II problem. The crowding of the lower anterior teeth was relieved and alignment of the upper arch was achieved with full fixed appliance therapy, resulting in improved aesthetics and a stable occlusion at one year review.