Untitled Document

Volume 19, No.2 - November 2003

Original Articles

Hand-wrist and cervical vertebral maturation indicators: how can these events be used to time Class II treatments?
Keith Grave, Grant Townsend
Australian Orthodontic Journal 2003; 19: 33-45

A longitudinal index study of orthodontic stability and relapse
Richard Olive, Kaye Basford
Australian Orthodontic Journal 2003; 19: 47-55

Stability of combined Le Fort I maxillary advancement and mandibular reduction
Premjit Arpornmaeklong, Jocelyn Shand, Andrew Heggie
Australian Orthodontic Journal 2003; 19: 57-66

Comparison of radiation levels from computed tomography and conventional dental radiographs
Daniel Ngan, Om Kharbanda, Joseph Geenty, M. Ali Darendeliler
Australian Orthodontic Journal 2003; 19: 67-75

Distribution of the epithelial rests of Malassez and their relationship to blood vessels of the periodontal ligament during rat tooth development
Petrina Kat, Wayne Sampson, David Wilson, Ole Wiebkin
Australian Orthodontic Journal 2003; 19: 77-86

Case Report

Extraction treatment using a palatal implant for anchorage
Aldo Giancotti, Mario Greco, Raffaela Docimo, Claudio Arcuri
Australian Orthodontic Journal 2003; 19: 87-90

Abstracts

Hand-wrist and cervical vertebral maturation indicators: how can these events be used to time Class II treatments?
Keith Grave, Grant Townsend

Background: Ossification events in the hand and wrist and in the cervical vertebrae have been shown to occur at specific times before, during and after the adolescent growth spurt, but there is still debate about the applicability of these findings to the clinical management of Class II cases.
Aim: The aim of this study was to relate, on an individual basis, cervical vertebral maturation stages and hand-wrist ossification events to the timing of peak statural and mandibular growth in a group of indigenous Australians. Methods: Velocity curves for stature and mandibular growth were constructed for 47 boys and 27 girls, and maturation events were then plotted on the curves.
Results: For the majority of children, peak velocity in mandibular growth coincided with peak velocity in stature. Particular combinations of hand-wrist and cervical maturation events occurred consistently before, during or after the adolescent growth spurt.
Conclusion: Our findings are consistent with those for North American children and we believe that assessment by orthodontists of a combination of hand-wrist and cervical vertebral maturation stages will enhance prediction of the adolescent growth spurt, thereby contributing to a positive, purposeful and more confident approach to the management of Class II cases.

Aust Orthod J 2003; 19: 33-45

Received for publication: June 2003
Accepted: September 2003

A longitudinal index study of orthodontic stability and relapse
Richard Olive, Kaye Basford

Background: Previous studies of stability and relapse after orthodontic treatment report short-term stability is generally followed by slow relapse to the original condition. What these studies do not report is whether this relapse is continuous or interspersed with periods of improvement or stability.
Methods: A subjective 0-10 index of malocclusion was used to record post-treatment stability and relapse over 10 to 12 years following fixed appliance orthodontic treatment of 24 patients. The severity scores were plotted on timelines.
Results: Episodes of change, both favourable and unfavourable, were interspersed with episodes of stability. Conclusions: Changes in the first 3 and 12 months post-treatment are indicative of the 10 to 12 years post-treatment outcomes. This index may provide a useful instrument to analyze patients and/or their study models longitudinally.

Aust Orthod J 2003; 19: 47-55

Received for publication: June 2002
Accepted: September 2003

Stability of combined Le Fort I maxillary advancement and mandibular reduction
Premjit Arpornmaeklong, Jocelyn Shand, Andrew Heggie

Background: There have been reports that correction of severe Class III abnormality by single jaw surgery may invite relapse in the long-term. The purpose of this study was to retrospectively evaluate the stability of combined Le Fort I maxillary advancement and bilateral sagittal split osteotomies for mandibular reduction.
Methods: Thirty patients with a skeletal Class III malocclusion underwent bimaxillary surgery using rigid fixation and interpositional bone grafting of the maxilla. The average age was 24.4 years, and the mean follow-up period was 20 months (Range: 12-63 months). Post-operative changes were measured on lateral cephalometric radiographs using an anatomical best-fit technique.
Results: The maxilla was advanced, on average, 6.1 mm (SD: 1.8 mm) and repositioned superiorly at PNS 1.9 mm (SD: 2.1 mm). The mandible was repositioned posteriorly 5.6 mm (SD: 4.2 mm) at menton, which also auto-rotated superiorly. At follow-up, the maxilla relapsed horizontally 0.6 mm (SD: 1.1 mm, p < 0.01) with no significant vertical change. The maxillary central incisors were proclined and the interincisal angle was reduced. Menton relapsed anteriorly 1.4 mm (SD: 2.7 mm, p < 0.01), and gonion rotated superiorly 1.5 mm (SD: 2.3 mm, p > 0.001). In 67 per cent of cases menton moved anteriorly less than 2.5 mm. The overjet and overbite did not change significantly.
Conclusions: The data show that 12-months post-operatively maxillary advancement combined with mandibular setback was relatively stable in the horizontal and vertical planes.

Aust Orthod J 2003; 19: 57-66

Received for publication: November 2002
Accepted: April 2003

Comparison of radiation levels from computed tomography and conventional dental radiographs
Daniel Ngan, Om Kharbanda, Joseph Geenty, M. Ali Darendeliler

Background: With the increasing use of computer tomography (CD) in oral diagnosis and treatment planning concern has been expressed about the high levels of radiation used, and the associated risks.
Objectives: The purpose of this study was to compare the radiation doses of facial CT scans with the radiation doses taking a lateral cephalometric radiograph, a panoramic radiograph (OPG), an occlusal film, and an intra-oral periapical radiograph.
Methods: An Alderson-Rando anthropomorphic phantom head was used for the analysis. Thirty-six lithium fluoride thermoluminescent dosimeters were placed in the phantom head in locations representing radiosensitive sites. Standard facial CT scans and conventional radiographs (lateral cephalometric, OPG, maxillary occlusal, intra-oral periapical) were then taken of the phantom head.
Results: The following radiation doses were measured: maxillo-mandibular CT scan, 2.1 mSv; maxillary CT scan, 1.40 mSv; mandibular CT scan, 1.32 mSv; lateral cephalometric radiograph, 0.005 mSv; OPG, 0.010 mSv; maxillary occlusal, 0.007 mSv; intra-oral periapical radiograph, 0.005 mSv.
Conclusions: CT scans produce significantly more ionising radiation than conventional radiographs. This factor should be taken into account when considering a CT scan as an alternative to a survey with conventional radiographs. While CT scans offer many advantages over conventional radiography the high radiation dose to patients, and the cost of this procedure should be considered.

Aust Orthod J 2003; 19: 67-75

Received for publication: March 2003
Accepted: July 2003

Background: There is some evidence that the epithelial cell rests of Malassez partition the root surface from the periodontal ligament blood vessels, and may protect the root from resorption.
Objective: The aim of the present study was to determine the distributions of the epithelial rests of Malassez (ERM) and blood vessels in the periodontal ligament (PDL) of the developing rat first molar before, during and after emergence.
Methods: Four Sprague-Dawley rats were sacrificed at two days, one week, two weeks, three weeks, four weeks and six weeks of age. After processing, the maxillae were embedded in paraffin, and sectioned longitudinally and transversely. The sections were stained with a double immuno-histochemical technique which utilised a keratin antibody AE1-AE3 (1:2,000) and an endothelial antibody Factor VIII (1:10,000) to enable simultaneous labelling of ERM and blood vessels. ERM and blood vessel counts were obtained from the mesio-buccal roots of thee week, four week and six week-old rats, whilst qualitative observations were made for the earlier developmental stages.
Results: ERM cells and cell clusters were found in the tooth third of the PDL width at the three, four and six week stages. Cells and cell clusters increased in number with age, especially in the upper third of the mesio-buccal root. The largest numbers of cells and clusters were found on the distal surfaces of the roots in all age groups. Cells and clusters in all root surfaces increased from three to four weeks, but decreased from four to six weeks. The greatest number of blood vessels was found in the bone-side third of the PDL. The distal surface had the highest proportion of blood vessels, and the palatal surface the least proportion. The number of blood vessels in all surface quadrants did not vary much from three to four weeks of age, but increased from four to six weeks of age, possibly as a reaction to tooth emergence and occlusal function. Physiological root resorption was only observed after tooth emergence, and appeared to be related to loss of continuity of the ERM network and the incursion of blood vessels.
Conclusions: Orthodontic root resorption can be regarded as an exaggerated response to loss of PDL homeostatic control, possibly mediated by the epithelial rests of Malassez.

Aust Orthod J 2003; 19: 77-86

Received for publication: January 2003
Accepted: May 2003

Case Report

Extraction treatment using a palatal implant for anchorage
Aldo Giancotti, Mario Greco, Raffaela Docimo, Claudio Arcuri

Aim: To describe the use of Straumann Orthosystem implants for orthodontic anchorage.
Methods: The Straumann Orthosystem consists of a titanium palatal implant and connected device, which can be used when absolute anchorage is required. In the present study the implant was placed in the midline at the junction of the alveolar process and hard palate. The implant was osseointegrated 13 weeks after placement. A palatal arch attached to the implant and upper first molar bands was used to provide stationary anchorage in a 23 year-old female with protruding upper anterior teeth and moderate crowding of both arches.
Conclusion: A palatal implant provides stationary anchorage for retraction of anterior maxillary teeth.

Aust Orthod J 2003; 19: 87-90

Received for publication: August 2002
Accepted: July 2003