Australian Orthodontic Journal最新文献

Tooth agenesis is the most common developmental dental anomaly and it is frequently associated with other dento-skeletal disturbances, such as structural variations of other teeth, late dental eruption, transpositions and crowding. Except for the third molars, the mandibular second premolars are the most commonly missing teeth. Oral rehabilitation of patients with missing mandibular premolars often requires a multi-disciplinary approach, and usually results in prolonged treatment time and a greater burden of care. An understanding of the aetiology and clinical features of hypodlontia is essential for the planning phase and the outcome of treatment. The purpose of the present review is, therefore, to discuss the aetiology of hypodlontia as well as to evaluate the clinical options available for the treatment of missing mandibular second premolars. An insight into future research directions and their clinical applications will also be discussed.

Orthodontics continues to be a profession anchored in traditional technology using appliances that cause inflammatory periodontal ligament (PDL) responses. Existing concepts of biological tooth movement based largely on histological tissue observations and the application of physical principles require major reassessment. In the next millennium, the genome revolution and knowledge of protein production and control could lead to the genetic correction of dentofacial anomalies and pain-free, biomolecular methods of malocclusion correction and long-term stability. A fundamental change is likely to be the abolition of bracket systems and their replacement with preprogrammed microchips driven by computers, and the control of PD[ blood vessels and cells by pharmacological targeting. Future survival of the profession will depend on a radically different specialist who will be educated with a postgraduate curriculum based on molecular biology and computer engineering.

Background: 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.

Methods: 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 (lJ.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 mini- implants 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.

Results and conclusion: 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.

This paper questions the adequacy of orthodontists' full appreciation of the issues associated with the routine prescription of extra- oral radiography, particularly that related to a high risk of thyroid gland exposure to ionising radiation. There does not appear to be adequate application of the ALARA principle in the consileration of justifiable options to minimise the cumulative effects of radiation exposure in young patients.

Introduction: 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.

Objective: 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'.

Materials and methods: 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.

Results: 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.

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

The intrusion of the maxillary first molar is indicated when occlusal clearance is needed for prosthetic rehabilitation. Maxillary molar intrusion may be undertaken using skeletal anchorage systems to avoid complicated mechanics delivered by conventional intra-oral fixed appliances. In the present case report, the efficient use of orthodontic miniscrew anchorage by applying simple mechanics for true maxillary first molar intrusion is described. This was followed by the rehabilitation of the mandibular first molar spaces with implant prostheses. A 16-year-old female patient had masticatory difficulty due to the bilateral overeruption of the maxillary first molars and carious mandibular first molars. True intrusion of each maxillary first molar was achieved using zygomatic and palatal paramedian miniscrews placed in line with the central axis of the teeth. Simultaneously, alignment of the upper arch was achieved via fixed appliance therapy. Using two orthodontic miniscrews to intrude each maxillary molar, orthodontic treatment was simplified by eliminating the need for miniplate placement by extensive surgery and the creation of intra-oral multiunit anchorage. Masticatory efficiency was improved by increasing the occlusal table with prosthetic rehabilitation of the mandibular first molar spaces with dental implant prostheses.

Background: A Class Il malocclusion is the most frequent sagittal skeletal disharmony presenting for orthodontic treatment. A transverse interarch discrepancy ITID) may be considered as a possible functional cause of a Class 11 relationship.

Objective: 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.

Methods: 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 (NJ perpendicular was similarly measured in each group.

Results: 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).

Conclusion: 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.

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

Method: 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).

Results: 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 lICC) for the weighted data for conventional, individual and average scenarios were 0.955 0.906 - 0.986 CI), 0.998 (0.995 - 0.999 CII. 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.

Conclusion: 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.