Volume 32 (2016): Issue 2 (January 2016)

To compare the effects of the Herbst appliance and the Activator at the completion of two-phase treatment, with respect to the vertical facial pattern (VFP) and to identify possible predictors of treatment effect.

Pretreatment, post-treatment and overall cephalometric change data were used to assess the dental and skeletal effects. Results for the change in mandibular length were also compared with changes reported for an untreated external control group.

Clinically significant dental and skeletal changes (including mandibular incisor proclination and overjet reduction) were characteristics of both treatment methods. Any increases in mandibular length and chin prominence were not greater than those expected following natural growth. The pretreatment VFP remained essentially unaltered, while mean changes as a result of treatment were similar for brachyfacial, mesofacial, and dolichofacial subjects. No predictive factors were identified.

Clinicians are advised to expect significant overjet reduction and mandibular incisor proclination with either treatment method. Significant skeletal change may be observed in growing subjects; however, any increase in mandibular length or chin projection is not likely to be beyond the limit set by nature. While there will be some individual variation, no significant long-term alteration in the pretreatment vertical facial pattern should be expected with either treatment. Long faces will remain long and short faces will remain short.

Rapid maxillary expansion is performed to correct a skeletal transverse deficiency of the maxilla, which is a frequently- encountered orthodontic anomaly. Strontium ranelate (SrR) is a novel agent that has a dual action, involving anti-resorptive and bone-forming effects. The aim of this study was to evaluate the effects of systemically applied SrR on osteoblastic bone formation after maxillary expansion on the mid-palatal suture of rats using histological and immunohistochemical tests.

A total of 24 Wistar rats were randomly divided into two equal groups. In all animals, five-day inter- premaxillary expansion was applied and maintained for a seven-day retention period, during which 625mg/kg/day SrR diluted with saline solution was administered orally to the experimental group. The rats were sacrificed and the tissues prepared for histological and immunohistochemical examinations after the retention period.

Osteoblastic activity and the width of the blood vessels in the suture area were significantly increased in the SrR group compared with the control group (p < 0.05). Ossification was also observed to be active under light microscopy by staining with hematoxylin and eosin in the experimental group. Immunohistochemical labelling performed using osteonectin, osteocalcin, TGF-β and VEGF antibodies revealed significant immunoreactivity in the experimental group (p < 0.05).

It may be concluded that SrR contributed to stimulatory osteogenesis in the expansion region. Therefore, a retention period may be shortened and relapse possibly reduced, following the application of SrR after the expansion.

A Class II malocclusion is the most frequent sagittal skeletal disharmony presenting for orthodontic treatment. A transverse interarch discrepancy (TID) may be considered as a possible functional cause of a Class II relationship.

The purpose of the present study was to determine transverse interarch width dimensions before and after orthodontic therapy and their possible relationship with increased mandibular projection following treatment.

The sample included 40 adolescent patients who were divided into two groups, one possessing and one without a transverse discrepancy. Interarch width differences (including ICWD, IPWD, IMWD, IAWD) were measured before and after treatment, and Pogonion (Pog) to Nasion (N) perpendicular was similarly measured in each group.

The differences in arch and alveolar width dimensions between the two groups (including ICWD, IPWDI, IPWDII, IMWD, IAWD) before treatment were statistically significant (p < 0.05). A comparison of Pog to N perpendicular between the two groups showed that mandibular protrusion after treatment in the transverse discrepancy group was 2.6 ± 1.3 mm, while mandibular protrusion after treatment in the group without a transverse discrepancy was 0.6 ± 0.3 mm. The statistical comparison showed that the differences were significant (p < 0.01).

A transverse interarch discrepancy may have a functional relationship with mandible retrusion. If a transverse discrepancy is corrected via orthodontic treatment, the mandible may spontaneously protrude.

Appropriate screening and referral is important in delivering effective and timely orthodontic treatment. In New Zealand, dental therapists are usually the initial contact for oral health care (including the assessment of malocclusion) in child and adolescent patients.

To investigate the orthodontic screening and referral practices of dental therapists in New Zealand.

Ten registered dental therapists from Auckland and Dunedin were interviewed using a semi-structured approach. Participants were selected based on years of work experience, where they practised, their educational background, and their sector of work (private/public).

Three main themes were identified: (1) the orthodontic screening and referral process; (2) the factors affecting orthodontic referral; and (3) their attitudes towards orthodontic treatment. Orthodontic screening and referrals were uniform among public dental therapists but varied for private dental therapists with regard to the type of malocclusions referred, the frequency of the referrals and to whom they referred. Factors that affected orthodontic referrals included participants’ orthodontic educational background, work experience, Continuing Professional Development courses attended, and the opinions of orthodontists and/ or dentists. Dental therapists found that most patients were receptive to the idea of orthodontic treatment, but that cost was a major concern. Dental therapists were enthusiastic about the development and use of resources that could aid in the orthodontic screening and referral process.

This study has provided valuable insights into the current orthodontic referral process of New Zealand dental therapists. Variations among public and private therapists were identified. The implementation of an orthodontic referral guideline was viewed favourably by dental therapists.

Titanium alloy mini-implants have become popular in recent times and have been extensively used and studied. Although corrosion resistance of orthodontic materials has always been of concern, this property has been the least explored. The present study aimed to assess the composition, surface characterisation and corrosion resistance of five commercially available mini-implants by assaying ion release in artificial saliva.

Ten mini-implants each from five companies were obtained: Group 1 – AbsoAnchor (Dentos Inc, South Korea); Group 2 – Microimplant Anchorage System (MIA, Biomaterials Korea); Group 3 – The Orthodontic Mini Anchorage System (TOMAS, Dentaurum, Germany); Group 4 – mini-implants (Denticon, Maharashtra, India); Group 5 – orthodontic mini-implants (J.J.Orthodontics, Kerala, India). One mini-implant from each group was subjected to characterisation and surface microstructure analysis using Energy Dispersive Atomic Spectrometry (EDAX) and Scanning Electron Microscope (SEM), respectively. Ten miniimplants were immersed for 30 days in Fusayama-Meyer artificial saliva solution and the release of titanium, aluminium and vanadium ions was detected with Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). The Kruskal-Wallis test was used for multi-variate analysis. In order to determine the significant differences between the groups on independent samples, the Mann-Whitney U test (bi-variate analysis) was applied.

All groups showed machining defects but surface pitting after immersion was mostly evident in Group 4. Although the composition of all the implants was comparable, there was a statistically significant difference in the Ti, Al and V release between Group 4 – the group with maximum release – and Group 2, the group with least release.

Neural crest cells make up a transient migratory population of cells found in all vertebrate embryos. Great advances have been made over the past 20 years in clarifying the molecular basis of neural crest induction and, although much still remains unclear, it appears that it is a process involving several factors acting at different stages of embryogenesis. In the future, an understanding of the precise mechanisms involved in orofacial development, even at the earliest stages, may well be of use to all clinicians interested in the management of these tissues.

The present study was designed to determine if the early addition of noggin (a bone morphogenetic protein (BMP) antagonist) and/or the late addition of BMP4 would increase the expression of the transcription factors: Msx-1, Snail, Slug and Pax-7.

This involved an assessment of the effects of early addition ( Days 0 to 3) of noggin and/or the late addition (Days 4 to 7) of BMP4 on the expression of the neural crest markers by human embryonic stem cells, co-cultured for eight days on a feeder layer of mouse PA6 cells.

The expression of the neural crest markers Pax-7, Msx-1, Slug, and Snail by human embryonic stem cells is likely to be affected by the addition of noggin and BMP4. Not all of these effects will necessarily be significant. The late addition of BMP4 is likely to significantly increase the expression of Pax-7 by human embryonic stem cells (hESCs), when compared with the effects of co-culturing with stromal cell-derived inducing activity, alone. The early addition of noggin and the late addition of BMP4 are likely to significantly increase the expression of Msx-1 by hESCs, when compared with the late addition of BMP4, alone. The hESC results support those from animal ESC studies that the late addition of BMP4, especially, may result in the differentiation of neural crest precursors.

The validity, reliability and inter-method agreement of Peer Assessment Scores (PAR) from acrylic models and their digital analogues were assessed.

Ten models of different occlusions were digitised, using a 3 Shape R700 laser scanner (Copenhagen, Denmark). Each set of models was conventionally and digitally PAR-scored twice in random order by 10 examiners. The minimum time between repeat measurements was two weeks. The repeatability was assessed by applying Carstensen’s analysis. Inter-method agreement (IEMA) was assessed by Carstensen’s limit of agreement (LOA).

Intra-examiner repeatability (IER) for the unweighted and weighted data was slightly better for the conventional rather than the digital models. There was a slightly higher negative bias of -1.62 for the weighted PAR data for the digital models. IEMA for the overall weighted data ranged from −8.70 – 5.45 (95% Confidence Interval, CI). Intra-class Correlation Coefficients (ICC) for the weighted data for conventional, individual and average scenarios were 0.955 (0.906 – 0.986 CI), 0.998 (0.995 – 0.999 CI). ICC for the weighted digital data, individual and average scenarios were 0.99 (0.97 – 1.00) and 1.00. The percentage reduction required to achieve an optimal occlusion increased by 0.4% for the digital scoring of the weighted data.

Digital PAR scores obtained from scanned plastic models were valid and reliable and, in this context, the digital semi-automated method can be used interchangeably with the conventional method of PAR scoring.

A considered space analysis aims to predict the combined mesiodistal widths of unerupted permanent canine and premolars. A miscalculation can lead to the application of inadequate and irreversible treatments.

To assess the level of agreement between predictions generated by three methods (Moyers’ predictive tables at the 50th and 75th percentiles and Tanaka-Johnston’s equations) on the sum of unerupted teeth compared with measurements derived from cone beam computed tomography, considered in the present study as a ‘gold standard’.

The study sample was comprised of children (N = 26) aged 8–13 who visited the Department of Dentistry. Moyers’ predictive tables and the Tanaka-Johnston equation were applied to ascertain the space requirements. Cone beam computed tomography was performed on each patient and the volumetric data analysed. A concordance correlation coefficient between each method’s predictions was applied.

The three methods tended to overestimate the cone beam computed tomography readings and were not able to entirely capture the variability of the sum of the unerupted teeth. Moyers’ 50th percentile estimate revealed a more balanced distribution between over-and underestimation.

The present study suggested that Moyers’ 50th percentile is the predictive method with the lowest absolute error and is preferred for clinical use.

The aim of this study was to determine the effects of nociceptin/orphanin FQ peptide receptor (N/OFQ receptor) antagonist on orofacial pain induced by experimental tooth movement in rats.

A total of 36 male Sprague-Dawley rats weighing 200–300 g were divided into six groups: a control group, force group, force+saline intraperitoneal group, force+saline periodontal group, force+UFP-101 ([Nphe¹,Arg¹⁴,Lys¹⁵]N/OFQ-NH₂; antagonist for N/OFQ receptor) intraperitoneal group, and force+UFP-101 periodontal group. Closed coil springs were ligated between the upper incisors and first molar to exert an orthodontic force (40 g) between the teeth. Injectable administration dosages were 30 μl saline or 30 μl saline containing 0.03 mg/kg UFP-101. Following the injections, orofacial pain levels were assessed through directed face grooming (mouth wiping). Statistical analyses were performed in SPSS 17.0 (Statistical Package for the Social Sciences) and p values less than 0.05 were considered as statistically significant.

Orofacial pain levels were significantly higher in the force group than in the control group. Orofacial pain levels differed significantly between the force group, force+saline periodontal group and force+UFP-101 periodontal group, but were similar between the control group, force+UFP-101 intraperitoneal group and force+saline intraperitoneal group. Moreover, orofacial pain levels did not differ between the force group, force+saline intraperitoneal group and force+UFP-101 intraperitoneal group.

Periodontal, but not intraperitoneal, administration of UFP-101 could alleviate orofacial pain induced by experimental tooth movement in rats, suggesting that periodontal N/OFQ receptors participate in orofacial pain induced by experimental tooth movement.

The purpose of this study was to evaluate the effects of short-term expansion treatment using the quad-helix appliance on dentofacial morphology in orthodontic patients presenting with a hyperdivergent facial pattern.

The treatment group consisted of 40 patients with a hyperdivergent facial pattern, who were treated for maxillary incisor crowding with a quad-helix appliance during the mixed dentition period. Lateral cephalograms taken at the start (T0) and end (T1) of the treatment were obtained as a course of care. A similar number of patients, who possessed the same type of facial pattern and who remained untreated, were assigned to a control group. Two consecutive lateral cephalograms of each untreated patient were taken at the same time points as T0 and T1. All cephalograms were traced, analysed and compared between the two groups.

The treatment changes as a result of the quad-helix appliance were expressed in an upward rotation of the mandible (2.34°) and distal tipping and impeded mesial movement of the maxillary first molars. Significant differences were evident between the treatment and control groups.

Quad-helix appliance treatment can be appropriate for significantly decreasing the mandibular plane angle in hyperdivergent patients presenting with moderate maxillary incisor crowding and a positive overjet and overbite.

The aim of the present study was to investigate whether the same orthodontic information can be obtained from study models or photographs of study models in order to assess the Index of Orthodontic Treatment Need (IOTN). The study also aimed to assess inter- and intra-examiner reliability in the assessment of orthodontic treatment need.

Thirty sets of start and finish study models, demonstrating a range of malocclusions, were non-randomly obtained from patients treated at the University of Manchester Dental Hospital. The start models demonstrated a range of malocclusions (according to The British Standard Institute Incisor Classification 1983) of varying complexity.

Six photographic views of each set of study models were taken against a dark background. Millimetric distances were determined by using dividers to measure photographic distances and actual distances in millimeters from a ruler embedded in the image. Four examiners assessed the study models and photographs of the models in a random order and the Aesthetic and Dental Health components of the IOTN were recorded.

There were no statistically significant differences in the IOTN scores from photographs of study models compared with IOTN scores from study models of the same patient.

The IOTN scores derived from photographs of study models are valid and reliable measures of malocclusion.