Volumen 33 (2017): Heft 1 (January 2017)

The aim of the present study was to evaluate the dentoskeletal and airway effects of three different functional appliances (Frankel-2, Trainer and X-Bow) in prepubertal Class II division 1 patients.

The sample consisted of 54 patients with a Class II relationship as a result of mandibular retrognathia and relative maxillary constriction. Group I included 15 patients treated with a Frankel-2 appliance. Group II consisted of 14 patients treated with a T4-K Trainer. Group III consisted of 15 patients treated with the X-Bow appliance. Group IV consisted of 10 untreated Class II patients who served as a control group. Pretreatment (T1) and post-treatment (T2) cephalograms were used to evaluate dentoskeletal and airway changes. Parametric one-way variance analysis (ANOVA) and a paired t-test were used to perform statistical analysis.

The decrease in SNA angle was significant in groups I and III, compared with the control group (p < 0.05). SNB angle and Co-GN length changes from T1 to T2 were statistically significant in groups I and II (p < 0.05), but not relative to the control group. The upper and lower incisors were significantly retruded and protruded, respectively, in all treatment groups (p < 0.05). Except PNS-AD2 and MAS measurements in group I, nasopharyngeal and oropharyngeal airway dimensions did not significantly change from T1 to T2 in all groups.

The Frankel-2 and X-Bow appliances were efficient in restricting the forward growth of the maxilla. The Frankel-2 and Trainer appliances produced a larger sagittal increase in mandibular length than the X-Bow appliance. Lower incisor proclination was more pronounced in the X-Bow group. The effect of the treatment protocols was similar and matched the control group with respect to the airway.

The aim of this study was to determine the effects of an elastic mandibular advancement (EMA) appliance on upper airway dimensions, most constricted area (MCA) of the airway, and snoring in a sample of obstructive sleep apnoea (OSA) patients of varying severity.

Forty-seven male subjects were classified into two groups comprising12 controls and 35 suffering from OSA. The OSA group was further divided into three subgroups based on their apnoea-hypopnoea index (AHI). All subjects completed an Epworth questionnaire and an overnight home sleep test before (T1) and at the end of the study (T2). OSA subjects were provided with a custom-made EMA appliance. Cone beam computed tomographic images were obtained for each subject at T1 and T2. Airway parameters were measured and summarised by grouping. The differences in the measurements T1 – T2 were compared using repeated measures analysis of variance (rmANOVA) and p ≤ 0.05 was considered statistically significant.

The use of the EMA produced a statistically significant increase in the nasopharyngeal, oropharyngeal, MCA, and total airway volume. Although sleep apnoea patients reported a reduction in snoring time, particularly in moderate and severe OSA groups, the level of improvement was not statistically significant. Patients with moderate and severe OSA demonstrated significant decreases in their AHI and Epworth scores.

EMA is effective in reducing OSA severity and changing airway dimensions in OSA patients, specifically in the moderate and severe cases.

The aim of this study was to investigate the frictional resistance (FR) and surface topography of newly available polycrystalline alumina (PCA) ceramic brackets characterised by a yttria-stabilised zirconia (YSZ) coating of the slots, compared with monocrystalline alumina (MCA) ceramic brackets and stainless steel (SS) brackets.

The FR was investigated using a universal testing machine. The test groups included PCA (Clarity Advanced, 3M Unitek, CA, USA) and MCA (Inspire Ice, Ormco, CA, USA). The control group included SS brackets. A sliding test was performed for each bracket type with three bracket-wire angulations (0°, 5°, 10°). A total of 225 sliding tests were performed in a dry environment, and 225 tests were performed in a wet environment of artificial saliva. A scanning electron microscope was used for qualitative assessments. The surface topography of the bracket slots was quantitatively assessed using an optical profilometer.

In the dry environment, the overall FR values were significantly lower for PCA and SS brackets compared with MCA brackets (p < 0.001), but no significant difference was found between PCA and SS brackets. In the wet environment, there were no significant differences between the bracket groups and their overall FR values. There was a significant correlation between the overall FR and the bracket-wire angulation values (p < 0.001). The bracket slot surface topography revealed that the PCA bracket slots had the highest roughness values, followed by SS and MCA brackets (p < 0.001). There was no significant correlation between the roughness values of the bracket slots and the FR in a passive configuration for all bracket types.

A yttria-stabilised zirconium coating of the PCA ceramic bracket slots might be a positive approach to apply for the reduction of FR.

Delayed dental development has been linked with tooth agenesis. Research aimed at dental age estimation in subjects with third molar agenesis has been minimal.

To investigate the association between dental stage of development and third molar agenesis.

A total of 700 orthopantomograms (OPTs) were obtained for this study. The age of the subjects ranged from 10 to 16 years (13.66 ± 1.50 years). The subjects were divided into two groups of which group 1 consisted of 350 patients (175 females and 175 males) with third molar agenesis and group 2 (control group) had all third molars present. The control group matched the study group for gender and chronological age (CA). Dental age (DA) was estimated from the OPTs using the Demirjian method for all included subjects.

The mean CA and DA in the third molar agenesis group were 13.81 ± 1.60 years and 13.72 ± 1.65 years, respectively (p > 0.05). The mean CA and DA in the control group were 13.51 ± 1.38 years and 14.50 ± 1.12 years, respectively (t = 18.25, p > 0.000). CA-DA difference between the two groups was highly significant (t = 12.43, p > 0.000). Gender differences were not detected. Furthermore, no differences were noted in dental age compared with chronological age in cases of unilateral versus bilateral third molar agenesis or in one jaw versus two jaws (p > 0.05).

Dental development was delayed in subjects with third molar agenesis but the delay in dental age was not affected by the severity or site of agenesis.

The objective of the present study was to evaluate the effect of three different surface treatment protocols on the shear bond strength (SBS) of metal brackets to Vita Enamic^® and Lava^™ Ultimate CAD/CAM hybrid ceramics.

A total of 60 crowns were milled and divided into one of three etching groups which used 9.6% hydrofluoric acid, 35% phosphoric acid and 50 μ aluminum oxide microetching. The surface morphology of the ceramic was observed after each etching treatment using a scanning electron microscope to characterise the etched surface. Lower left first molar tubes (Ormco^™) were bonded with light-cure composite, stored in artificial saliva for one week and subsequently thermocycled. The SBS test was performed using an Instron 5566 machine. Adhesive Remnant Index (ARI) scores were also assigned to determine the mode of bond failure. Data were analysed using an Independent Sample t-test.

The SBS of all groups, except the HFA Enamic^® group, were significantly lower than the mean SBS of the enamel control group (8.8 MPa). The mean shear bond strength values of Enamic^® were significantly higher than those of Lava^™ Ultimate (p-values < 0.05).

Statistically, only Enamic^® treated with HFA exhibited sufficient SBS when compared with the enamel control. Adhesive failures between the bracket base and adhesive were the predominant mode of failure in all groups except in the PA Lava^™ Ultimate group.

The present study considered the effect of orthodontic friction in an evaluation of the relationship of craniofacial pattern and surface micro-roughness of fixed appliances as determinants of treatment response and time.

Brachyfacial (BF; N = 17) and dolichofacial (DF; N = 18) patients treated by canine retraction using sliding mechanics, were identified. One archwire and one bracket per patient (those of the hemi-arch showing the fastest space closure of 4 mm) were subjected to confocal scanning microscopic analysis. Total treatment duration, sliding time, tooth movement rate, topographical surface average roughness (R_a), root mean square roughness (RMS), surface-kurtosis (SK), and surface-skewness (SS) were recorded and compared between groups using the Mann-Whitney U test. Correlations between final micro-roughness and treatment time were investigated using Pearson’s coefficient within each craniofacial type (a = 0.05). The post-treatment appliance surfaces were examined by SEM.

BF patients recorded a significantly higher sliding time, lowest retraction rates, and greatest final R_a and RMS (p < 0.001). A comparison of total treatment time and final SK and SS values yielded no significant differences. Significant positive correlations between sliding time and final R_a were identified in both groups.

Compared with DF subjects, BF patients registered higher friction between the orthodontic components, required longer sliding time, and showed lower retraction rates.

The evolution of adhesive dentistry and the addition of nanoparticles has heralded an improvement in the mechanical properties of adhesives. Thus, the aim of the present study was to evaluate the effects produced by carbon nanotubes (CN) added to two adhesives used for indirect bonding by an examination of the shear bond strength (SBS) and location of bond failure.

One hundred and sixty bovine incisors were randomly divided into eight groups (N = 20): (1) indirect bonding with Sondhi adhesive; (2), (3) and (4) indirect bonding with Sondhi adhesive into which CN at 0.5%, 0.25% and 0.05% concentrations were incorporated; (5) indirect bonding with Concise adhesive; (6), (7) and (8) indirect bonding with Concise adhesive into which CN at 0.5%, 0.25% and 0.05% concentrations were incorporated. Following etching with 37% phosphoric acid and the placement of brackets, maximum shear bond strength (SBS) was measured with a mechanical testing machine. The location of bond failure was evaluated using the Adhesive Remnant Index (ARI). The SBS between groups and ARI scores were statistically analysed (p < 0.05).

There was no statistical difference (p > 0.05) in SBS or ARI.

CN addition to Concise and Sondhi adhesives did not influence the SBS and the ARI of the brackets. Therefore, in the conditions of this experiment, there was no benefit in the addition of CN to orthodontic adhesives.

Intermaxillary elastics are widely used in corrective orthodontic treatment particularly for the interdigitation of buccal segments and the correction of the midline. However, latex has been known to cause allergy, which may restrict elastic use. As alternative materials, non-latex elastics are available. However, clinicians must be aware of their mechanical properties, especially those of deformation and force degradation that affect these materials over time.

The aim of this study was to compare force degradation and deformation of³/₁₆” non-latex and latex elastics supplied by several manufacturers.

Special acrylic plates were fabricated to incorporate orthodontic brackets to which elastics were attached and stretched to a distance of approximately 20 mm. The internal diameter and force magnitude of each elastic was measured at time intervals of 0, 24, 72 and 504 hours. The samples were stored in artificial saliva at room temperature during the entire experimental period.

Latex elastics showed smaller and more uniform deformation than the non-latex elastics. The non-latex elastics showed greater degradation at all time intervals (p < 0.001). The Morelli brand delivered greater force than other brands for both the latex and non-latex elastics at all time intervals (p < 0.05). The G&H latex elastics showed greater force degradation in comparison with the other brands (p < 0.05). The evaluation of the Dentaurum and Orthopli non-latex elastics showed greater degradation (p < 0.05).

The non-latex elastics showed greater force degradation than the latex elastics. Of the latex elastics, G&H showed greater force degradation, and for the non-latex elastics, those made by Dentaurum and Orthopli degraded most.

Digital models have become more widely accepted for orthodontic diagnostic purposes. Intraoral scanners have the advantage of eliminating the need for conventional impressions. The aim of the present study was to assess the reliability and reproducibility of the Lythos intraoral scanner and to determine if a significant advantage is delivered over stone model and caliper measurements in tooth width and Bolton ratio accuracy.

The study comprised 30 typodont models for which conventional alginate impressions and digital scans were obtained to generate stone and digital models, respectively. Mesiodistal tooth width measurements and Bolton ratios were obtained with either calipers and stone models or with Digicast (Ormco Lythos digital model software, Ormco, CA, USA) software using digital models. Pearson’s correlation coefficients tested intra-examiner reliability. Interclass correlation coefficients were used to assess agreement between examiners (reproducibility). The differences in the mean tooth width measurements and Bolton ratios from the typodont values and either the digital or conventional method were used to assess validity by applying two tailed t-tests.

The measurements obtained from the Lythos and stone models had near perfect intra-examiner agreement (Pearson ≥ 0.98). The inter-examiner reproducibility for tooth widths, anterior Bolton and overall Bolton ratio was high and similar for both methods (Lythos scanner Interclass correlation coefficient (ICC) above 0.89, stone models ICC above 0.92). Stone model measurements were statistically twice as accurate as those derived from the digital system (0.032 mm versus 0.074 mm). There were no significant differences in accuracy between the methods for Bolton calculations. Clinically, there was no difference between the methods for tooth width measurements and Bolton calculations.

The Lythos system is as reliable and reproducible as conventional calipers and stone models in tooth width measurements and Bolton calculations. The caliper method presents a statistically more valid tooth width measurement technique but the clinical significance of this is questionable.

Considered rotation of the occlusal plane and the maxillomandibular complex during orthognathic surgery is an approach that enables optimisation of the functional and aesthetic outcomes of surgical-orthodontic treatment for the correction of a variety of dentofacial deformities.

The objectives of this study are to: (1) retrospectively evaluate the stability of clockwise and anti-clockwise rotation of the occlusal plane during orthognathic surgery, and (2) compare the findings with the stability of orthognathic surgery in which no significant occlusal plane rotation occurs.

Data were collected from a sample of 31 adult patients (22 females and nine males) treated by one orthodontist in private practice and at the University of Western Australia from 1992–2008. Patients received a Le Fort I osteotomy and BSSO to reposition the maxilla and mandible, respectively. The patients were separated into three groups defined by no occlusal plane rotation; clockwise occlusal plane rotation; or anti-clockwise occlusal plane rotation. Lateral cephalograms were taken at four time periods during treatment: T1 (pre-surgery), T2 (immediately post-surgery), T3 (six weeks post-surgery), and T4 (longest follow-up). The cephalograms were digitised and analysed using a customised cephalometric analysis (QuickCeph Studio, CA, USA) and landmarks were transferred via cranial base and maxillary superimpositions for each patient from T1 sequentially to T4.

Clockwise rotation of the occlusal plane was highly stable one year following surgery and showed comparable results with cases treated without occlusal plane rotation. Anti-clockwise rotation of the occlusal plane was less stable and showed significant relapse of the occlusal plane angle towards the pre-surgical value during the post-surgical observation period.

Clockwise rotation of the occlusal plane during orthognathic surgery appears highly stable. Anti-clockwise occlusal plane rotation during orthognathic surgery appears less stable. Further studies are needed to evaluate the longer-term stability of clockwise and anti-clockwise rotation of the occlusal plane during surgical-orthodontic treatment.

Increased mobility of teeth in adult patients with advanced periodontal disease causes posterior bite collapse, which is characterised by mesial inclination of the molars and vertical dimension loss, often resulting in bimaxillary dentoalveolar protrusion.

A case is reported of successful comprehensive periodontal/orthodontic treatment of a 51-year-old woman presenting with bimaxillary dentoalveolar protrusion accompanied by severe crowding in the mandibular arch and flaring of the maxillary anterior teeth as a result of posterior bite collapse due to periodontal disease.

Miniplates and fixed appliances were used to upright the mandibular molars and create space for the retraction of the anterior teeth. Prior to orthodontic treatment, the patient underwent periodontal therapy to create a healthy oral environment. The treatment outcomes, including the periodontal condition, were stable 24 months after the conclusion of active orthodontic care.

The outcome demonstrates that anchorage control with miniplates is advantageous for the treatment of bimaxillary dentoalveolar protrusion and posterior bite collapse due to periodontal disease.