Volume 32 (2016): Issue 1 (January 2016)

The present study was undertaken to assess the relationship between the mandibular muscles and dentofacial skeletal morphology in children with different underlying vertical facial patterns, using three-dimensional computed tomography (3D-CT).

Thirty children (mean age 12.24 ± 1.57 years) underwent cranial CT examination for diagnostic purposes. 3D-CT images were reconstructed for the evaluation of the cross-sectional size, volume, and spatial orientation of the masseter and medial pterygoid muscles. These muscle parameters were also assessed in relation to the vertical facial pattern, gender and skeleto-dental form.

Significant differences were found in muscular angulation for subjects with different underlying patterns. Greater masseter volumes were associated with increased facial width. Greater intermolar widths were found in brachyfacial subjects, with less acute muscular angulations in relation to horizontal reference lines, compared with dolichofacial subjects. This was also more obvious in the maxillary arch.

Clinicians should note the likely differences in masseter and medial pterygoid orientation and volume in subjects with different underlying vertical facial patterns and that these differences may, in turn, be related to both facial skeletal width and naturally-occurring transverse dental arch dimensions.

The objective of the present study was to determine which of six bonding protocols yielded a clinically acceptable shear bond strength (SBS) of metal orthodontic brackets to CAD/CAM lithium disilicate porcelain restorations. A secondary aim was to determine which bonding protocol produced the least surface damage at debond.

Sixty lithium disilicate samples were fabricated to replicate the facial surface of a mandibular first molar using a CEREC CAD/CAM machine. The samples were split into six test groups, each of which received different mechanical/chemical pretreatment protocols to roughen the porcelain surface prior to bonding a molar orthodontic attachment. Shear bond strength testing was conducted using an Instron machine. The mean, maximum, minimal, and standard deviation SBS values for each sample group including an enamel control were calculated. A t-test was used to evaluate the statistical significance between the groups.

No significant differences were found in SBS values, with the exception of surface roughening with a green stone prior to HFA and silane treatment. This protocol yielded slightly higher bond strength which was statistically significant.

Chemical treatment alone with HFA/silane yielded SBS values within an acceptable clinical range to withstand forces applied by orthodontic treatment and potentially eliminates the need to mechanically roughen the ceramic surface.

To test the hypothesis that enamel surface deproteinisation with different concentrations of bromelain in association with 10% papain increases the shear bond strength (SBS) of brackets bonded with orthodontic composite and resin modified glass ionomer cement (RMGIC).

Orthodontic brackets were attached according to the following protocols to 195 bovine incisors, which were acquired and divided into 13 groups: 1) Transbond XT (TXT) according to the manufacturer’s recommendations; 2) Deproteinisation with 3% bromelain (BD) plus 10% papain and TXT; 3) 6% BD plus 10% Papain and TXT; 4) RMGIC, without enamel deproteinisation and without acid etching; 5) RMGIC, with 3% BD plus 10% papain and without acid etching; 6) RMGIC, with 6% BD plus 10% papain and without acid etching; 7) attachment using RMGIC following etching with polyacrylic acid; 8) 3% BD plus 10% papain, attachment using RMGIC and etching with polyacrylic acid; 9) 6% BD plus 10% papain, and attachment using RMGIC following etching with polyacrylic acid; 10) etching with 37% phosphoric acid and attachment using RMGIC; 11) 3% BD plus 10% papain, etching with 37% phosphoric acid and attachment using RMGIC; 12) 6% BD plus 10% papain, etching with 37% phosphoric acid and attachment using RMGIC; 13) deproteinisation with 2.5% sodium hypochlorite (NaOCl), etching with polyacrylic acid and RMGIC. After bonding, the brackets were removed by a universal mechanical testing machine, which recorded shear bond strength at failure. The material remaining on the tooth was assessed using the adhesive remnant index (ARI).

Deproteinisation with 3% and 6% bromelain gel plus papain significantly increased the shear bond strength (p < 0.05), when acid etching was performed with phosphoric acid, followed by primer application and attachment using Transbond XT (Group 3) and when attached with RMGIC without etching. Deproteinisation with 6% bromelain gel plus papain significantly increased (p < 0.05) the ARI score only when attachment was performed using RMGIC, without etching (Group 6).

Deproteinisation with bromelain associated with papain in a gel increased the shear bond strength and is recommended before orthodontic bracket attachment.

The aim of the present study was to investigate and compare the cephalometric effects of a conventional Hyrax expansion screw and a memory screw on the skeletal and dentoalveolar structures and soft tissues of the face.

Thirty-two patients with a maxillary transverse deficiency were divided into two groups. A memory-screw group included 17 patients (nine females and eight males), while a Hyrax-screw group was comprised of 15 patients (eight females and seven males). The mean ages of the subjects in the memory-screw and Hyrax-screw groups were 13.00 ± 1.29 and 12.58 ± 1.50 years, respectively. Lateral cephalograms were taken of the patients at the beginning of the treatment (T1), at the end of expansion (T2) and retention periods (T3). The mean expansion period was 7.76 ± 1.04 days in the memory-screw group and 35.46 ± 9.39 days in the Hyrax-screw group. The Shapiro-Wilk Normality test was used to determine whether the investigated parameters were homogeneous. To determine the treatment changes within the groups, a paired t-test and Wilcoxon Signed Rank test were applied to the homogeneous and non-homogeneous parameters, respectively. A comparison between the groups was carried out using the Student’s t-test for homogeneous parameters and the Mann-Whitney U test for all others.

A results summary indicates that mid-palatal sutural opening and subsequent important skeletal and dental expansions were obtained in all patients. The maxilla moved anteriorly and inferiorly in both groups while the mandible rotated inferiorly and posteriorly but to a greater extent in the memory-screw group.

The newly-developed memory expansion screw takes advantage of rapid and slow maxillary expansion protocols. The suture is opened and the maxilla expanded with relatively lighter forces over a shorter time. The RME using the memory screw resulted in similar sagittal and vertical changes to those produced by the Hyrax screw.

Following the debonding of orthodontic brackets, the removal of residual adhesive from the enamel surface is required. Published adhesive removal protocols present conflicting advice.

The present study evaluated the surface roughness of enamel after debonding and instrumentation with non-traditional orthodontic polishing systems.

The facial aspects of 35 extracted human incisor teeth were scanned with a surface profilometer for surface roughness prior to the bonding of orthodontic brackets. After debonding, residual adhesive was removed with a 12-fluted titanium carbide bur. The teeth were randomly divided into seven groups (N = 5 per group) and the enamel surface was polished with one of seven products. All samples were re-scanned for surface roughness and subjectively evaluated via SEM.

There was no significant difference in enamel surface roughness between the groups when compared using surface profilometry. Visual observations from the SEM evaluations demonstrated differences in the enamel surface at the microscopic level that were not detected by profilometric analysis.

The present study found no statistically significant difference in mean enamel smoothness change from pretreatment to post-treatment between the seven polishing methods studied via profilometer surface reading measurements. An SEM analysis showed visual differences in enamel striations viewed at 1000× magnification in a comparison of traditional versus non-traditional polishing methods.

To assess the sagittal soft tissue morphology of patients with acromegaly in comparison with a healthy control group.

Twenty-seven patients with acromegaly (11 male, 16 female; mean age 47.3 ± 11.5 years) and 30 healthy subjects (15 male, 15 female; mean age 42.2 ± 17.4 years) were included in the study. Linear and angular measurements were made on lateral cephalograms to evaluate soft tissue and skeletal characteristics. The intergroup comparisons were analysed with the Student’s t-test.

Facial convexity (p < 0.01) and the nasolabial angle (p < 0.001) were reduced in patients with acromegaly, whereas nose prominence (p < 0.01), upper lip sulcus depth (p < 0.01), upper lip thickness (p < 0.01), basic upper lip thickness (p < 0.01), lower lip protrusion (p < 0.05), mentolabial sulcus depth (p < 0.05) and soft tissue chin thickness (p < 0.001) were increased. Anterior cranial base length (p < 0.05), the supraorbital ridge (p < 0.01), the length of the maxilla and mandible (p < 0.001, p < 0.01, respectively) were significantly increased, and mandibular prognathism was an acromegalic feature (p < 0.05).

Acromegalic coarsening and thickening of the craniofacial soft tissues was identified from lateral cephalograms, which may therefore contribute to early diagnosis when evaluated together with other changes caused by the disease.

To determine the effect of varying the transverse cant of the anterior teeth on orthodontists’ and laypeople’s perceptions of smile aesthetics, and the influence that smile height has on this perception.

A 20-year-old Chinese female with an aesthetic smile and normal occlusion was chosen and agreed to participate. Digital pictures of her posed smile were taken and manipulated to create three smile height variations: low, medium, or high. Each variation was further manipulated to create varying degrees of transverse anterior tooth cant. Fifty-six laypeople and 40 orthodontists participated as raters of the dental and facial impact of the altered smile images.

The orthodontists more commonly and precisely identified the transverse cants of the anterior teeth and the detracting influence on smile aesthetics compared with laypersons. The orthodontists accepted a lesser range of anterior transverse cant. Increased smile heights enhanced the capability of all raters to detect a transverse cant and reduced the acceptable cant range. In addition, an increased smile height worsened the detracting effects of the transverse anterior cant in all raters’ perceptions of smile aesthetics. An increased display of teeth and angulation of an anterior cant increased the ability of raters in both groups to detect differences.

Transverse cants of anterior teeth can affect orthodontists’ and laypeople’s perceptions of smile aesthetics. Smile height and incisor display were significant factors that affected the orthodontist’s and layperson’s perceptions of smile aesthetics, and suggested that a description of the detracting effect of an anterior transverse cant should also consider smile height.

A transverse occlusal cant is an important aesthetic factor used by clinicians during orthodontic diagnosis and review. It is important to appreciate that there is a difference in perception between orthodontic professionals and patients (laypeople). The extent of this perceptual difference and influencing factors could help the clinician set more appropriate treatment goals.

To compare the analgesic effect of topical benzocaine (5%) and ketoprofen (1.60 mg/mL) after 2 mm activation of 7 mm long delta loops used for maxillary en-masse orthodontic space closure.

Twenty patients (seven males, 13 females, 15–25 years of age, mean age of 19.5 years) participated in a randomised crossover, double-blind trial. After appliance activation, participants were instructed to use analgesic gels and record pain perception at 2, 6, 24 hours and 2, 3 and 7 days (at 18.00 hrs), using a visual analogue scale ruler (VAS, 0–4). Each patient received all three gels (benzocaine, ketoprofen, and a control (placebo)) randomly, but at three different appliance activation visits following a wash-over gap of one month. After the first day, the patients were instructed to repeat gel application twice a day at 10:00 and 18:00 hrs for three days. The recorded pain scores were subjected to non-parametric analysis.

The highest pain was recorded at 2 and 6 hours. Pain scores were significantly different between the three groups (Kruskal–Wallis test, p < 0.01). The overall mean (SD) pain scores for the benzocaine 5%, ketoprofen, and control (placebo) groups were 0.89 (0.41), 0.68 (0.34), and 1.15 (0.81), respectively. The pain scores were significantly different between the ketoprofen and control groups (mean difference = 0.47, p = 0.005). All groups demonstrated significant differences in pain scores at the six different time intervals (p < 0.05) and there was no gender difference (p > 0.05).

A significant pain reduction was observed following the use of ketoprofen when tested against a control gel (placebo). The highest pain scores were experienced in patients administered the placebo and the lowest scores in patients who applied ketoprofen gel. Benzocaine had an effect mid-way between ketoprofen and the placebo. The highest pain scores were recorded 2 hours following force application, which decreased to the lowest scores after 7 days.

To determine changes in mandibular position after the treatment of patients presenting with Class II division 2 malocclusions and to test the null hypothesis that there is posterior displacement of the mandible in these patients, in comparison with a control group of Class II division 1 subjects.

The assessed data consisted of pre- and post-treatment cephalometric radiographs of 77 subjects identified with Class II division 1 and Class II division 2 malocclusions matched according to age, gender and treatment duration. All completed fixed appliance orthodontic treatment. The changes in the position of point B, Pogonion and Articulare were determined at the end of treatment by superimposing the cephalometric radiographs on Sella-Nasion line at Sella. Thirteen cephalometric parameters including the distance between Basion and Articular (Ba-Art) were measured at each stage.

In both groups, SNB angle, SNPog angle and Ba-Art distance showed no statistically significant changes. Pogonion was displaced significantly in a forward and downward direction in the growing group, with no significant differences identified between Class II division 1 and Class II division 2 subjects.

The null hypothesis that there is posterior displacement of the mandible in Class II division 2 malocclusion is rejected. The growth pattern of the mandible in both divisions of a Class II malocclusion after orthodontic treatment was found to be similar. (Aust Orthod J 2016; 32: 73–81)

To demonstrate the use of the Invisalign appliance in lower incisor extraction cases.

Twelve patients, consecutively treated by the removal of a single lower incisor and Invisalign appliances, were selected from the author’s private practice. Pretreatment, treatment and post-treatment photographic records were obtained and are presented.

All cases completed treatment, with a mean treatment time of 42 weeks. Fifty percent of the cases required a brief period of refinement (average six weeks) at the end of the initial projected treatment period.

The Invisalign appliance, in correctly diagnosed cases, with careful ‘ClinCheck’ set-ups and good clinical monitoring, can routinely produce satisfactory outcomes in patients who require the removal of a lower incisor.

The aim of the present study was to assess the skeletal, dental and soft tissue effects of a specific treatment protocol in consecutively treated patients who presented with a Class III malocclusion. Treatment involved the use of a Hybrid Hyrax (HH) in the maxilla, a Mentoplate in the mandible and the application of continuous intra-oral Class III elastics.

The treated group was comprised of seven males and seven females (mean pretreatment age 10.4 ± 1.7 yr, range 7.8 – 12.9 yr). Treatment changes were analysed on lateral cephalograms taken 6–12 months prior to commencing treatment (T1) and at the finish of the orthopaedic phase (T2). Where a normality assumption was met, a parametric paired-sample t-test was used to assess the change differences at T1 and T2. For non-normal data, a non-parametric Wilcoxon sign rank test for related samples was used to assess T1 and T2 differences. The level of statistical significance was set at p < 0.05 (2-tailed).

The average sagittal changes showed an improved SNA angle of 2.1 ± 2° (p = 0.002), an ANB angle of 1.9 ± 1.8° (p = 0.002), a Wits improvement of 3.4 ± 2.7 mm (p < 0.001) and an overjet reduction of 2.0 ± 2.2 mm (p = 0.005). There were no statistically significant correlations found between the age at T1, age at treatment start and age at T2 and the changes identified in the cephalometric variables (T2-T1).

The HH-Mentoplate Class III treatment protocol induced a mean Wits improvement of 3.4 mm in the maxillary and mandibular sagittal base relationship at the functional occlusal level. This was primarily achieved by sagittal maxillary skeletal protraction with negligible effects on the mandible, facial vertical dimension and the incisor angulations. A controlled clinical study with larger sample sizes and longer follow-up times is needed.

Hemimandibular hyperplasia (HH), also known as hemimandibular hypertrophy, is characterised by excessive unilateral three-dimensional growth of the mandible after birth. Vertical unilateral elongation of the mandible becomes clinically evident as a rare form of vertical facial asymmetry. Aberrant growth of the facial skeleton affects the developing dentition and the dental compensatory mechanism is usually unable to maintain optimal occlusal relationships. The resulting malocclusion is effectively managed by combined surgical-orthodontic care to address the facial, skeletal and dental problems that confront clinicians. Orthodontists are advised to assess patients with HH during the post-treatment retention stage for continuing mandibular growth and assess the stability of treatment outcomes with long-term follow-up and records as required.

To present a case of hemimandibular hyperplasia treated successfully by combined surgical-orthodontic care and evaluated for stability over a seven-year follow-up period.

Surgical-orthodontic management was accomplished in four stages: 1) pre-surgical orthodontic; 2) surgical; 3) post-surgical orthodontic; and 4) post-treatment orthodontic retention. Complete orthodontic records, including extra- and intra-oral photographs, study models, and cephalograms plus panoramic radiographs were taken at the pretreatment, post-treatment, and seven-year orthodontic retention time-points.

Facial, skeletal and dental goals were achieved in the three planes of space and the long-term stability of the treatment results was shown during a post-treatment orthodontic retention period of seven years.

Hemimandibular hyperplasia is a true growth anomaly which may be managed effectively. Clinicians may expect successful long-term correction and stability by utilising a comprehensive surgical-orthodontic treatment approach.